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HOVO is an on demand app for ordering trucks in Egypt. We cover 8 different types of vehicles that include the Dababa, Suzuki Bolan, Tricycle, Winch, Jumbo, Dababa Box, Suzuki Ravi Pickup and the Jumbo Box. The vehicle arrives within 20 minutes (shortest waiting time in Egypt) and the client is able to track the order throughout the entire trip. We are also 25% cheaper than the competitors.

HOVO

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OHL Roundup: Brayden Gillespie perfect as Storm rout Otters 8-0

* * Achievement unlocked: With more than ‘4 billion’ in total votes -- almost half the population of earth voted for startups! JUST KIDDING! Some companies had a to accumulating their votes. unique approach In 2021, decided to host to highlight the backbone of the future - tech startups! for the first time in forever (make sure you sing it in Anna’s voice), HackerNoon.com Startups of The Year More than 44,000 startups were nominated all across the globe, spanning over 4,553 cities. That’s.Just.Spiffy! To see who is a winner in each respective city, visit and pick a city. The name at the top of the list is the winner. (Compromised awards are under review.) startups.hackernoon.com The will announce the winners per region in their respective cities. Startups Winners Announcement Series We’d like to take a moment here and thank every single person who cast a vote and every single company, both nominated and not nominated yet this year. Furthermore, we thank you for existing and opening more opportunities for the wonders of the future to come. Even if you don’t win anything today, you’ve won something much more valuable - our hearts <3 Okay, sorry for the long introduction. Below are all the Startups Winners: Startups of the Year (SOTY) in Africa Johannesburg, South Africa With more than 900 votes cast, #SOTY calls.... MiBRAND Thank you for connecting businesses and consumers, great job! Lagos, Nigeria With 836 votes in the bag, let’s give it up for... Goodtalent Thanks for helping tech companies build great engineering teams. Cape Town, South Africa Want to learn more about finance and use that knowledge to make better financial decisions? Look no further. Introducing winner of Startups of The Year, Cape Town: Revix With 527 votes cast, it seems like a lot of people have more money in their pockets thanks to . Revix Mahé, Seychelles With around 515 votes cast, #SOTY summons... DAOLaunch Thank you for bridging the gap between investors and startups. Lusaka And the winner for #SOTY in Lusaka is... ComGrow Thanks to them, people here are getting closer to the reality of the digitization of village banking. Nairobi, Kenya With 252 votes cast, UTU came out top as the Startup of The Year. Thanks for building the trust infrastructure of the internet to help businesses and consumers engage and transact in a more reliable way. Yaoundé Accounting for more than 73% of total votes, CamPay won this award fair and square. Thank you for making sending and receiving payments easier between online merchants. Abuja, Nigeria A proud winner in the prestigious capital of Nigeria, Elesaro deserves all the plaudits it gets. is a suite crowdfunding protocol built on BSC, Reward, Equity, Lending & NFT Marketplace. Congratulations! Elesaro Dar Es Salaam, Tanzania Jamii Africa is the name that will always be engraved on the #SOTY trophy. As a mobile micro-health insurance, Jamii Africa has done a great job for the health sector in Tanzania. Kigali, Rwanda Another #SOTY medal in the bag for none other than …wait for it… BAG Innovation BAG Innovation applies Gamification to offer real-time access to experience-based learning for University students in East Africa. Everybody loves playing games, but using games to learn in school is on another level. Gauteng, South Africa And the award goes to... Planet42 Thanks for democratising mobility by enabling people ignored by banks to get access to a personal vehicle through a car subscription service. Once again, congratulations! Port Harcourt, Nigeria Cryptocurrency is the present and the future, as we’ve all come to know. FLITBASE makes these digital assets more accessible to everyone. #SOTY is proud to add you to our Hall of Fame. Cairo, Egypt With 18 votes won out of the 91 cast, it seems there was fierce competition. Congratulations to... SubsBase for winning Startups of The Year. SubsBase allows businesses to manage their subscribers, automate recurring billings, set pricing plans, and monitor subscription KPIs. Tunis, Tunisia Come one, come all! Witness the greatness of yet another wonderful startup in the #SOTY. Thank you... VYND for providing a fully integrated digital platform to help venue owners better serve their customers and grow their businesses. Stellenbosch, South Africa BankTech connects clients to a payment network where it provides a convenient interface to meet various payments needs. You’ve won #SOTY proudly! Pretoria #SOTY acknowledges... Grays Pharmaceuticals Thank you for all you do. Lekki, Nigeria Middletrust provides reliable escrow services in Africa. Congratulations on winning a #SOTY medal. Addis Ababa Thank you... Hello Solar for consistently accelerating sustainable energy solutions, especially for remote communities. With half of the votes cast, you beat the odds. Accra, Ghana UT Bank Ghana provides various commercial banking services to individuals and companies in Ghana. We cannot emphasize enough the importance of financial services to humankind. #SOTY is proud of all you do. Gîza, Egypt Big congratulations to... HOVO for winning this award. Your on-demand mobile app for ordering trucks is truly appreciated! Goma, Democratic Republic of Congo Congratulations for coming out on top of #SOTY, SillonBlue Technologies As an ICT Consulting and SaaS company, SillonBlue Technologies focuses on software and mobile app development, and data collection. Yaba, Nigeria With more than half of the votes cast, this nominee conquered undisputedly. Let’s give it up for... Kuda a no-fee full-service digital bank making banking affordable for all Africans on the planet. Morocco City Almes provides infrastructure and logistics services. Congratulations on earning a #SOTY medal. Dakar ShopMeAway provides families and businesses with new ways to shop around the world with reduced shipping costs. You deserve the plaudits you’ve received! Casablanca Sheaply provides crowd shipping and crowd shopping solutions. This reduces cost and improves efficiency on shipping and shopping. Congratulations on winning a #SOTY medal. Nguru, Nigeria Accounting for 88% of the votes, TradeBuza wins #SOTY almost flawlessly. TradeBuza is a tech-enabled commodities sourcing platform for commodities aggregators and out-grower schemes. Ikeja, Nigeria PropertyPro Nigeria is now pronounced Startup of the Year in Ikeja. Let’s admit, who doesn’t appreciate a platform built to search for real estate properties? Ibadan, Nigeria No Bank, No Problem! (That’s probably not their motto, by the way) Shield Finders is a fintech and financial service provider to the unbanked. Congratulation on winning most of the votes! 6 October City, Egypt Wuilt is a website builder where you can create your own Arabic website in under 5 minutes. Thank you for making this technology accessible to people. One #SOTY medal for you! Algiers The only nominee who outvoted all others, please give it up for... Yassir Thank you for providing convenient transport services using your app. Enugu In an area that usually suffers from inconsistent electricity, Greenage comes to the rescue with their green cape and spandex suit. Greenage Technologies is a Nigerian startup solving electricity problems in Nigeria using solar energy technology. Congrats, Greenage. Abeokuta, Nigeria A government organization creating opportunities for entrepreneurs and the unemployed - no one deserves the title Startup of The Year better than Ogun Innovate Congratulations! Ariana And the award goes to... E-Stores Factory a web platform that helps rent and manage e-shops for enterprises seeking to sell online. Thank you for making the (not a typo) more friendly! e-cosystem Benin City Health really is wealth. MOBicure provides mobile technology solutions for Africa's biggest health problems. Thank you for all you do. From #SOTY with love <3 Centurion GameZBoost offers white label gaming platforms, including online desktop solutions, fully responsive mobile and social platforms. Thank you for making the world a more fun place! Gaborone Augmenta Cyber Security provides services in cyber security, safe data storage, SCADA security, SAP Security, etc. Congratulations on winning 10/10 of the votes. You rock! Garki There can never be enough medical platforms in the world. Congratulations to... Wella Health an operator of a healthcare technology company intended to provide treatments and medicines for malaria. Thank you for all you do! Lilongwe Yellow is a digital platform enabling informal merchants in Africa. #SOTY welcomes you to its hall of fame. Make yourself at home ;) Luanda Access to finance is important for any company or sector to succeed. And no other company deserves the title Startup of The Year more than Deya the first Angolan and PALOP crowdfunding platform that aims to increase access to financing for social impact causes and entrepreneurs. . 10/10 will recommend Mombasa Life can be hard, and so a little humor helps ease these hardships. Congratulations to this political satire puppet show, The XYZ Show for winning #SOTY. Thanks for putting smiles on our faces. Port Louis Town Bet you’ve never heard of a Smartcup. Thanks to Intellicup that exists now, and therefore earns this startup a #SOTY badge.  Intellicup is a unique high-speed beverage dispensing solution with integrated smart technology. While this cup won’t be able to wake you up in the morning, you have to agree that it’s still pretty impressive. Rabat Atlan Space is a startup building AI to autonomously pilot any fixed-wing drone, to monitor and take measures over very large areas. You deserve the #SOTY medal. Réunion Imagine having the power to do ultrasound scans on your handheld device. OSCULT by Oscadi is a handheld ultrasound imaging device interfaced with the Apple iPad. Congratulations on making it into the #SOTY! Somerset West Winning the award fair and square is Sticitt a cashless payment platform that is also aimed at teaching learners at school the basics of finance. The future of the world would be in good hands when our children know how to adequately manage finances. Thank you for saving the world in advance. Thika Flowers make the world a beautiful place to live in. Wilmar Flowers exports summer flowers grown by small and medium-sized farmers from Kenya. Kudos for making the world beautiful, #SOTY is honored to have you in our Hall of Fame. Kampala, Uganda Yo-Waste Limited is an African startup that provides waste, recycling and “smart city” solutions to businesses and governments. Your #SOTY gold medal shines as much as you do <3 Harare, Zimbabwe The world is becoming more and more digital every day. Thanks to companies like Golix that provide services of digital currencies for people in Africa, the digitization of the world is becoming more robust. Freetown Easy Solar is a distribution company making energy, durable goods and financial services affordable and accessible through pay-as-you-go tech. Thumbs up! Kicukiro FOODLINE specializes in non-genetically-modified grocery farming and production lines. Winner Winner Chicken Dinner! #SOTY Goma, Democratic Republic of Congo Startups Nuru is a renewable and environmental company that specializes in the fields of storage micro-grids and solar energy. After racking up all the votes, #SOTY honors you. Abidjan, Côte d'Ivoire Digitech provides a fully integrated and cloud-based InsurTech platform to incumbent insurance companies. You are awesome! Durban Security can never really be enough. We’d like to honor Blue Security the title Startup of The Year, for specializing in the installation and monitoring of intruder detection systems, and in providing armed response services. Ikoyi And the Startup of The year goes to... Winich Farms an Agritech Startup leveraging tech to connect rural farmers to Finance & Market, thus, increasing productivity and cutting post-harvest loss. You rock! Lomé The last recipient of #SOTY in Africa calls for... Gozem a transport technology platform for Francophone West and Central Africa. Thank you for providing a platform for transportation. We are honored to have you! *Winners missing from this list will be added accordingly. More Information If you’re a winner, please answer ! If you’re a reader, participant, just a curious individual, consider answering one of our interviews . this interview here Read the FAQs about or . Startups here here To see all of the winners you may visit , pick any city and view the name that appears at the top. this site If you’re interested in partnering with us, we invite you to look through some of these or reach out to our business department. unique sponsorship options Perhaps creating your very own tickles your fancy or maybe you have a whole new idea for how we can partner! writing contest Thank you to all of our sponsors! We truly appreciate your contribution to the tech world and thus the future! The Startups Awards are sponsored by: , , , , , , , , , , Blockster Brex FreeCodeCamp LaunchDarkly Coil Udacity Udemy Vercel Asia Pacific Transgender Network Bybit Everscale Network This post was written and edited by Kien Dao and Joshua Omale. If you have any questions or concerns or would like to report a discrepancy please email ellen@hackernoon.com.

What are the Top Startups in Africa?

Authors: (1) Gopal Yadav, Department of Physics, Indian Institute of Technology & Chennai Mathematical Institute. Table of Links Abstract & Introduction Brief Review of Wedge Holography Emerging Multiverse from Wedge Holography Application to Information Paradox Application to Grandfather Paradox Conclusion Acknowledgements and References 3 Emerging Multiverse from Wedge Holography In this section, we discuss how one can describe multiverse from wedge holography. 3.1 Anti de-Sitter Background In this subsection, we construct a multiverse from AdS spacetimes. Let us first start with the simplest case discussed in 2. To describe multiverse, we need multiple Karch-Randall branes located at r = ±nρ such that bulk metric should satisfy Neumann boundary condition at the aforementioned locations. Extrinsic curvature on the Karch-Randall brane and its trace is computed as: Three descriptions of our setup are as follows: • d-dimensional boundary conformal field theory with (d − 1)- dimensional boundary. Boundary description: • All 2n gravitating systems are connected at the interface point by transparent boundary condition. Intermediate description: • Einstein gravity in the (d + 1)-dimensional bulk. Bulk description: We see that in the intermediate description, there is a transparent boundary condition at the defect; therefore multiverse constructed in this setup consists of communicative universes localized on Karch-Randall branes (see Figs. 2,3). Wedge holography dictionary for “multiverse” with 2n AdS branes can be stated as follows. 3.2 de-Sitter Background In this subsection, we study the realization of the multiverse in such a way that the geometry of Karch-Randall branes is of de-Sitter spacetime. Wedge holography with de-Sitter metric on Karch-Randall branes was discussed in [42] where the bulk spacetime is AdS spacetime and in [52] with flat space bulk metric. Before going into the details of construction of “multiverse” with de-Sitter geometry on Karch-Randall branes, first let us summarise some key points of [52]. Authors in [52] constructed wedge holography in (d + 1)-dimensional flat spacetime with Lorentzian signature. Karch-Randall branes in their construction have either geometry of d dimensional hyperbolic space or de-Sitter space. Since our interest lies in the de-Sitter space therefore we only discuss the results related to the same. Geometry of the defect is S d−1 . Wedge holography states that Third line in the above duality is coming from dS/CFT correspondence [53, 54]. Authors in [52] explicitly calculated the central charge of dual CFT which was imaginary and hence CFT living at the defect is non-unitary. The above discussion also applies to the AdS bulk as well. In this case one can state the wedge holographic dictionary as: branes are obtained as: • d-dimensional BCFT with (d − 1)-dimensional defect. Boundary description: • 2n gravitating systems with de-Sitter geometry connected to each other at the (d − 1)-dimensional defect. Intermediate description: • (d + 1)-dimensional Einstein gravity with negative cosmological constant in the bulk. Bulk description: First and third description are related to each other via AdS/BCFT correspondence and (d−1)- dimensional defect which is non-unitary CFT exists because of dS/CFT correspondence [53, 54]. de-Sitter space exists for finite time and then disappear. Another de-Sitter space born after the disappearance of previous one [55]. Therefore it is possible to have a “multiverse” (say M1) with de-Sitter branes provided all of them should be created at the same “creation time” [7] but this will exist for finite time and then M1 disappears. After disappearance of M1, other multiverse (say M2) consists of many de-Sitter branes born with same creation of time of all the de-Sitter branes. 3.3 Braneworld Consists of Anti de-Sitter and de-Sitter Spacetimes In this subsection, we have discussed the embedding of different types of Karch-Randall branes in the different bulks which are disconnected from each other. Authors in [55] have discussed the various possibilities of embedding of different types of branes, e.g., Minkowski, de-Sitter and anti de-Sitter branes in the same bulk. Existence of various branes are characterized by creation time τ∗. There is finite amount of time for which Minkowski and de-Sitter branes born and there is no cration time for anti de-Sitter branes. Out of various possibilities discussed in [55], it was pointed by authors that one can see Minkowski, de-Sitter and anti de-Sitter brane at the same time with creation time τ∗ = −π/2 in a specific bulk. In this case, branes have time dependent position. First we will summarise this result [10] and then comment on the realization of the same from wedge holography. Bulk AdS5 metric has the following form: One can construct doubly holographic setup from (19) using the idea of AdS/BCFT. Let us state the three possible descriptions of doubly holographic setup constructed from (19). Comment on the Wedge Holographic Realization of Mismatched Branes: • 4D quantum field theory (QFT) at conformal boundary of (19). Boundary description: • Dynamical gravity localized on 4D end-of-the-world brane coupled to 4D boundary QFT. Intermediate description: • 4D QFT defined in the first description has 5D gravity dual whose metric is (19). Bulk description: Due to covariant nature of AdS/CFT duality it remains the same if one works with the changed coordinates in the bulk i.e. different parametrisations of AdS does not imply different dualities [11] and therefore in the above doubly holographic setup, we expect defect to be 3-dimensional conformal field theory because 4-dimensional gravity is just FRW parametrization of AdS4 spacetime (20). Relationship between boundary and bulk description is due to AdS/CFT correspondence, in particular, this kind of duality was studied in [56] where bulk is de-Sitter parametrization of AdS4 and conformal field theory is QFT on dS3. As discussed in detail in appendix of [55] and summarised in this subsection that one can also have de-Sitter and Minkowski branes in this particular coordinate system (19). If one works with de-Sitter metric (21) on end-of-the-world brane then we expect defect CFT to be non-unitary. Due to dynamical nature of gravity on Karch-Randall brane, holographic dictionary is not well understood in the braneworld scenario. A Now let us discuss what is the issue in describing wedge holography with “mismatched branes”. Wedge holography has “defect CFT” which comes due to dynamical gravity on Karch-Randall branes. Suppose we have two Karch-Randall branes with different geometry, one of them is AdS brane and the other one is de-Sitter brane. Then due to AdS brane, defect CFT should be unitary and due to de-Sitter brane, defect CFT should be non-unitary. It seems that we have two different CFTs at the same defect. This situation will not change even one considers four branes or in general 2n branes. Hence, one may not be able to describe “multiverse” with mismatched branes from wedge holography. That was just an assumption. Common boundary of multiverses M1 and M2 (described in Fig. 5) can’t be the same even when geometry is (19) due to “time-dependent” position of branes. All the AdS branes in M1 can communicate with each other via transparent boundary conditions at the defect and similarly all the de-Sitter branes in M2 are able to communicate with each other. But there is no communication between M1 and M2 even in (19). Therefore we conclude that we can create multiverse of same branes(AdS or de-Sitter) but not the mixture of two. Hence issue of mismatched branes do not alter from wedge holography perspective too. Multiverse of AdS branes exists forever whereas multiverse of de-Sitter branes has finite lifetime [12] . [3] It seems that some of branes have negative tension. Let us discuss the case when branes are located at −nρ1 and nρ2 with ρ1 6= ρ2. In this case tensions of branes are (d − 1) tanh(−nρ1) and (d − 1) tanh(nρ2). Negative tension issue can be resolved when we consider ρ1 < 0 and ρ2 > 0 similar to [48]. Therefore this fixes the brains stability issue in our setup. This discussion is also applicable to the case when ρ1 = ρ2. [4] When we discuss multiverse then α and β will take 2n values whereas when we discuss wedge holography then α, β = 1, 2 [5] Explicit derivation of (14) was done in [42] for two Karch-Randall branes. One can generalize the same for 2n Karch-Randall branes. In this setup upper limit of integration will be different for different locations of Karch-Randall branes. [6] See [42] for the explicit derivation. Only difference is that, in our setup, we have β = 1, 2, ..., n. [7] Creation time is defined as the “time” when any universe born [55]. [8] In this case, warp factor will be different in the bulk metric. Exact metric is given in (45). [9] We thank J. Maldacena for comment on this. [10] For more details, see [55] [11] We thank K. Skenderis to clarify this to us and pointing out his interesting paper [56] [12] We thank A. Karch for very helpful discussions on the existence of de-Sitter branes and issue of mismatched branes in wedge holography. This paper is under CC 4.0 license. available on arxiv

Understanding Multiverse Construction through Wedge Holography

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Comprendre la construction du multivers grâce à l'holographie Wedge

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ウェッジホログラフィーによる多元宇宙構築の理解

웨지 홀로그래피를 통한 다중우주 구성 이해

Compreendendo a construção do multiverso por meio da holografia em cunha

Понимание конструкции мультивселенной с помощью клиновой голографии

Wedge Holografisi Aracılığıyla Çoklu Evren Yapısını Anlamak

Tìm hiểu cấu trúc đa vũ trụ thông qua hình ảnh ba chiều Wedge

通过楔形全息术理解多元宇宙的构造

Authors: (1) Gopal Yadav, Department of Physics, Indian Institute of Technology & Chennai Mathematical Institute. Table of Links Abstract & Introduction Brief Review of Wedge Holography Emerging Multiverse from Wedge Holography Application to Information Paradox Application to Grandfather Paradox Conclusion Acknowledgements and References 2 Brief Review of Wedge Holography • CF Td−1 living on the wedge of common boundaries of two AdSd’s. Boundary description: • Two Karch-Randall branes of geometry AdSd (Q1 and Q2) glued to each other at the interface point by a transparent boundary condition. Intermediate description: • Einstein gravity in (d + 1)-dimensional bulk, AdSd+1. Bulk description: Precisely, correspondence can be interpreted as: “Classical gravity in (d + 1)-dimensions has a holographic dual theory on the defect which is CFT in (d − 1)-dimensions”. Wedge holography is useful in the computation of the Page curve of black holes. Let us understand this connection. In the intermediate description, we consider a black hole on Q2 whose Hawking radiation will be collected by weakly gravitating bath Q1 (i.e., T1 < T2). To calculate the entanglement entropy in the intermediate description, one is required to use the semiclassical formula: where γ is the minimal surface in bulk. In wedge holography, there is one more extremal surface, Hartman-Maldacena surface [30], which starts at the defect, crosses the horizons, and meets its thermofield double. By plotting the entanglement entropies contributions of these surfaces, we can get the Page curve [2]. This paper is under CC 4.0 license. available on arxiv

A Brief Review of Wedge Holography

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Authors: (1) Gopal Yadav, Department of Physics, Indian Institute of Technology & Chennai Mathematical Institute. Table of Links Abstract Acknowledgment PART I Chapter 1: Introduction Chapter 2: SU(3) LECs from Type IIA String Theory Chapter 3: Deconfinement Phase Transition in Thermal QCD-Like Theories at Intermediate Coupling in the Absence and Presence of Rotation Chapter 4: Conclusion and Future Outlook PART II Chapter 5: Introduction Chapter 6: Page Curves of Reissner-Nordström Black Hole in HD Gravity Chapter 7: Entanglement Entropy and Page Curve from the M-Theory Dual of Thermal QCD Above Tc at Intermediate Coupling Chapter 8: Black Hole Islands in Multi-Event Horizon Space-Times Chapter 9: Multiverse in Karch-Randall Braneworld Chapter 10: Conclusion and Future outlook APPENDIX A APPENDIX B APPENDIX C Bibliography APPENDIX C C.1 Complex Extrinsic Curvatures and Riemann Tensors We can go from complex Riemann tensors to real Riemann tensors by using the following coordinate transformations: Similarly to calculate the second term is holographic entanglement entropy formula we use the following coordinate transformations: Hence by using equation (C.4) we can obtain the second term appearing in holographic entanglement entropy formula in terms of the real coordinates (t, x) using the coordinate transformations given below: C.2 HM-Like/IS Analytics/Numerics In the present appendix, we describe (i) the angular integrations utilized throughout the computation and the equation describing the area of a Hartman-Maldacena-like surface, and (ii) the process by which we estimate the turning point in the context of Island Surface entanglement entropy. C.2.1 HM-Like Surface Area C.2.2 IS Turning Point C.3 Hartman-Maldacena-like Surface Miscellania We present numerous r dependent functions that appear in the entanglement entropy formula to describe the Hartman-Maldacena-like surface at O(β 0 ) and O(β) in this appendix. We also calculated the equation of motion pertaining to the embedding function associated with the Hartman-Maldacena-like surface. • The r dependent functions appearing in equation (7.57) are given as: • In the case of the existence of higher derivative terms, the following have been used to compute the first and second terms of holographic entanglement entropy computation: and where • To derive the equation of motion associated with embedding t(r), we must compute the derivatives that result from equation (7.56): and where C.4 Island Surface Miscellania We enumerate the many functions that emerge from the entanglement entropy of the island surface at O(β) in this appendix. We additionally calculated the derivatives of the Lagrangian associated with the island surface here, which were utilized to calculate the equation of motion concerning the island surface’s embedding. • The following terms (λ3,4(r)) exist in the Wald entanglement entropy term (first term of holographic entanglement entropy (7.78)) of the island surface: where κλ3 and κλ4 being the numerical factors. • The r dependent functions appeared in the anomaly term (the second term of holographic entanglement entropy (7.78)) are as follows: • For the action associated with the island surface’s embedding (7.79), we obtained: and, and, C.5 Possible Terms Appearing in Holographic Entanglement Entropies Within this appendix, we provided all of the terms that could possibly be obtained by differentiating the Lagrangian of the M-theory dual, including O(R4 ) corrections. We have included all of the words associated with the Hartman-Maldacena-like surface in C.5.1, and all of the available terms of the island surface in C.5.2. C.5.1 Hartman-Maldacena-like Surface • √ −g (7.23): Associated with the Induced Metric The equation (C.30) suggests that in the large-N limit, (iii) and (iv) terms correspond to the most dominant terms. where there is no N dependence in G1(r) and G2(r). The terms (v) and (xii) are the most prominent in the large-N limit among all the terms stated above. where G3(r) and G4(r) have no N dependence. The terms (v) and (xii) are the most dominant in the large-N limit. Since, only first term is non-zero, and hence this contributes to the Lagrangian. For the above equation, we found that all the three non-zero terms scale as N, and hence we kept all the non-zero terms in the Lagrangian. C.5.2 Island Surface • √ −g (7.40): Associated with the Induced Metric In the large N limit, terms (iii) and (iv) turn out to be the most dominant. where G5(r) and G6(r) do not depend on N. We found that, terms (v) and (xii) dominate in comparison to other terms in the large N limit. where G7(r) and G8(r) independent of N and the most dominant terms are (v) and (xii) in the larg-N limit. This paper is under CC 4.0 license. available on arxiv

Aspects of Thermal QCD Phenomenology at Intermediate Gauge/'t Hooft Coupling: Appendix C

Aspects of Thermal QCD Phenomenology at Intermediate Gauge/'t Hooft Coupling: Bibliography

Authors: (1) Gopal Yadav, Department of Physics, Indian Institute of Technology & Chennai Mathematical Institute. APPENDIX B B.1 O(R4 ) Corrections to the M-theory metric of [15] in the MQGP limit near the ψ = 2nπ, n = 0, 1, 2- branches where Σ1 has the following form: B.2 Thermal fMN EOMs, their Solutions in the IR, 4DLimit and MχPT Compatibility In the following appendix, we’re going to discuss the independent EOMs associated with the metric perturbations fMN of (3.2) near the IR cut-off r0 up to leading order in N, the solutions they provide and constraints as well as values for the same in the decompactification limit of a spatial direction (that has an important role for showing proof of an all-loop non-renormalization of Tc at O(R4 )). Through such a manner, we are capable to calculate the values of the metric perturbations (in the deep IR) across the three-cycle S 3 (θ1, x, z) - the delocalized version of S 3 (θ1, ϕ1, ψ) -strictly speaking across the fiber S 1 (z) (the S 3 (θ1, x, z) is a S 1 (z) fibration across the vanishing two-cycle S 2 (θ1, x)) as well as another two-cycle S 2 (θ1, z) (which has also a S 1 (z)-fibration). A unique linear combination of contributions from fMN |S3(θ1,x,z) , close to the Ouyang embedding within the parent type IIB dual, shows up frequently in Tc computations and the LECs of SU(3)χPT Lagrangian at O(p 4 ) from MχPT in chapter 2 (from [2]). In chapter 2, we found that the aforementioned combination of integration constant has a negative sign (2.30). Here we will derive this constraint. The EOMs of the metric perturbations fMN (r) are worked out as follows: EOMs (B.3) have the following solutions: Utilizing (B.5), around r = r0, we obtained: • We solved (B.13) - (B.15) and obtained: B.3 M-Theory Metric Associated with Rotating Cylindrical Black Hole and Thermal Backgrounds • The following are O(β 0 ) components associated with the M-theory dual involving a rotating cylindrical black hole background in the MQGP limit differ from those derived in [15,66]. Apart from these components, rest of the components are same as given in (B.1) at O(β 0 ). where r 4 . (B.18) • The O(β) terms in the small ω-limit, remain the same as worked out in [1] and has been provide in (B.1). B.4 O(β) Contribution to the On-Shell Action Densities for the Rotating QGP Tc Calculation To derive the contribution that comes from the O(β) contributions in the on-shell action density for the black hole backdrop, write the metric in diagonal basis (3.118). The t − ϕ subspace’s unwarped metric could be expressed as: where and We can now write the metric in (t, ϕ) subspace and O(R4 ) correction to the same, i.e., fMN (r), where (M, N = t, ϕ) (we are concentrating exclusively on the t, ϕ) subspace). The metric’s tt component could be written as: implying Similarly, the ϕt component of the metric is written as: and therefore, The same is also applicable for the ϕϕ component: hence fϕϕ is obtained as: In the small-ω limit, γ = 1, hence the equation (B.19) simplified as: As a result, the structure of the M-theory metric for the black hole background in the small ω-limit in rotating quark-gluon plasma is the same as the structure of the M-theory metric without rotation. As a result, in the small ω-limit, the higher derivative corrections to the M-theory metric for the rotating cylindrical black hole and thermal backgrounds will be the same as obtained in [1]. As a result, the on-shell action densities associated with the rotating cylindrical thermal and black hole background will be identical to [3] (i.e. similar to 3.2) augmented by a factor of l, which is going to cancel out at the UV cut-off from both sides of the equation (3.131). B.5 Holographic Renormalization of Rotating Gravitational Backgrounds Here, we have discussed the holographic renormalization of rotating cylindrical black hole and thermal backgrounds used in 3.4. : Divergent parts of the M-theory on-shell action of the rotating cylindrical black hole background at O(β 0 ) have the following structure: • Rotating Cylindrical Black Hole Background UV-divergences appearing in the M-theory on-shell action of the rotating cylindrical black hole background at O(β 0 ) will be cancelled by the following term: We found that UV-divergence appearing in equation (B.32) will be cancelled by the following counter term: provided Divergent part of the M-theory on-shell action at O (β0) in the UV have the following form: • Rotating Cylindrical Thermal Background: where first and second terms in equation (B.36) are counter terms for the first and second terms in equation (B.35) and are given as below: This paper is under CC 4.0 license. available on arxiv

Aspects of Thermal QCD Phenomenology at Intermediate Gauge/'t Hooft Coupling: Appendix B

Authors: (1) Gopal Yadav, Department of Physics, Indian Institute of Technology & Chennai Mathematical Institute. Table of Links Abstract Acknowledgment PART I Chapter 1: Introduction Chapter 2: SU(3) LECs from Type IIA String Theory Chapter 3: Deconfinement Phase Transition in Thermal QCD-Like Theories at Intermediate Coupling in the Absence and Presence of Rotation Chapter 4: Conclusion and Future Outlook PART II Chapter 5: Introduction Chapter 6: Page Curves of Reissner-Nordström Black Hole in HD Gravity Chapter 7: Entanglement Entropy and Page Curve from the M-Theory Dual of Thermal QCD Above Tc at Intermediate Coupling Chapter 8: Black Hole Islands in Multi-Event Horizon Space-Times Chapter 9: Multiverse in Karch-Randall Braneworld Chapter 10: Conclusion and Future outlook APPENDIX A APPENDIX B APPENDIX C Bibliography Similarly, the profile function of the π-meson is given as [2, 83]: We showed that UV valued profile functions are [2, 83]: This paper is under CC 4.0 license. available on arxiv

Aspects of Thermal QCD Phenomenology at Intermediate Gauge/'t Hooft Coupling: Appendix A

Authors: (1) Gopal Yadav, Department of Physics, Indian Institute of Technology & Chennai Mathematical Institute. Table of Links Abstract Acknowledgment PART I Chapter 1: Introduction Chapter 2: SU(3) LECs from Type IIA String Theory Chapter 3: Deconfinement Phase Transition in Thermal QCD-Like Theories at Intermediate Coupling in the Absence and Presence of Rotation Chapter 4: Conclusion and Future Outlook PART II Chapter 5: Introduction Chapter 6: Page Curves of Reissner-Nordström Black Hole in HD Gravity Chapter 7: Entanglement Entropy and Page Curve from the M-Theory Dual of Thermal QCD Above Tc at Intermediate Coupling Chapter 8: Black Hole Islands in Multi-Event Horizon Space-Times Chapter 9: Multiverse in Karch-Randall Braneworld Chapter 10: Conclusion and Future outlook APPENDIX A APPENDIX B APPENDIX C Bibliography CHAPTER 10 - CONCLUSION AND FUTURE OUTLOOK In this part of the thesis, we have studied the resolution of information paradox using various proposals, e.g., island proposal, doubly holographic setup, and wedge holography. In this process, we addressed the following issues: • How do the higher derivative terms in the gravitational actions affect the Page curve? • How to obtain the Page curve of black holes with multiple horizons, e.g., Schwarzschild de-Sitter black hole? • Can we describe the “Multiverse” using wedge holography? We started with a very simple example and considered the Reissner Nordström black hole in the presence of O(R2) terms as higher derivative terms, which is a non-holographic model. We considered the two kinds of HD terms: Gauss-Bonnet term and general O(R2) as considered in [141]. Following is the summary of key results obtained in chapter 6 which is based on [10]. • The Page curves of Reissner Nordström black hole are shifting towards later times or earlier times when Gauss-Bonnet coupling (α) increases or decreases. This implies that Page time is being affected due to the presence of HD terms. As soon as islands contribute to the entanglement entropy of Hawking radiation, we get the information from the black hole. Hence, “dominance of islands” in the entanglement entropy of Hawking radiation to compute the Page curve is affected by the higher derivative terms. • We found that scrambling time is affected when we have some other general O(R2) terms, including the Gauss-Bonnet term. In contrast, it is unaffected when we consider only the Gauss-Bonnet term as the higher derivative term. • We showed that our results are consistent with the literature by taking the α → 0 limit. We recover the results of [172] in this limit. We studied the black hole information problem in chapter 8 based on the paper [12] and proposed a method to resolve the information paradox of black holes with multiple horizons. We focused on the Schwarzschild de-Sitter (SdS) black hole, which has two horizons: black hole and de-Sitter horizons. To obtain the Page curve of the black hole, we inserted thermal opaque membranes on both sides so that an observer living on the black hole side can access only the radiation of the black hole patch. We used the island proposal to define the radiation regions in the black hole patch. In this case, gravity is not negligible enough, but one can use the island proposal in the approximation that the observer is very far away from the black hole. Hence, we can use the island proposal. We computed the entanglement entropy of Hawking radiation in the absence and presence of the island surface. After plotting these contributions together, we obtained the Page curve of the black hole patch. We also studied the effect of temperature on the Page curves of black holes. We found that lowtemperature black holes take too much time to deliver the information out of the black holes compared to high-temperature black holes. In the language of entanglement islands, this result is interpreted as follows. “Dominance of islands” and “information recovery” and hence Page time is higher for low-temperature black holes because when islands contribute to the entanglement entropy, we get information from the black hole. In this kind of black hole, it is not possible to obtain the Page curve of the Schwarzschild de-Sitter black hole as a whole due to asymmetrical regions on both sides of the SdS black hole. We constructed the doubly holographic setup from a top-down approach in chapter 7 based on our work [11]. In our setup, the bulk is the eleven-dimensional M-theory uplift inclusive of O(R4) corrections of type IIB string dual constructed in [1]. The external bath to collect the Hawking radiation is a non-conformal thermal QCD bath. We obtained the Page curve of the eternal neutral black hole by computing the entanglement entropies of Hartman-Maldacena and island surfaces in the absence and presence of O(R4) terms. When O(R4) terms are absent, then we obtained the entanglement entropies by computing the areas of extremal surfaces, whereas in the presence of higher derivative terms, we used Dong’s formula to calculate the entanglement entropies. Let us compare the doubly holographic setup constructed from the bottom-up approach and our setup. • Bottom-up double holography with CFT bath: Three descriptions of the doubly holographic setup is given as below. d-dimensional BCFT living at AdSd+1-boundary with (d − 1)-dimensional defect. – Boundary Description: Gravity on d-dimensional end-of-the-world brane coupled to d-dimensional BCFT via transparent boundary condition at the defect. – Intermediate Description: d-dimensional BCFT has its own holographic dual which is AdSd+1. – Bulk Description: Top-down model has three following descriptions similar to the bottom-up model. • M theory brane description of top-down double holography with QCD bath: QCD2+1 is living at the tip of the conifold i.e. at r = 0. – Boundary-like Description: Black M5-brane which contains black hole coupled to QCD2+1 bath living at M2 brane. – Intermediate Description: QCD2+1 has holographic dual which is eleven dimensional M theory. – Bulk Description: Following are the key results that we obtained in chapter 7. • In doubly holographic setups, it was found that one could get the Page curve with massive gravity on the end-of-the-world brane. In our setup, we explicitly showed that this is not the case in the top-down model. We computed the spectrum of graviton on the end-of-the-world brane and found that one could get the Page curve with massless graviton localized on the end-of-the-world brane. • We found that O(R4 ) terms do not affect the Page curve in this setup because contributions to the entanglement entropies are large-N exponentially suppressed. This exponential large-N suppression exists because of massless graviton on the brane. • We showed that no boundary terms arise on the end-of-the-world brane even in the presence of O(R4 ) terms in the bulk, and end-of-the-world brane turns out to be a “fluxed hypersurface” with non-zero tension. • Hartman-Maldacena surface entanglement entropy also exhibits “Swiss-Cheese” structure in large-N scenario. In chapter 9 (which is based on the work done in [13]), we used wedge holography to describe multiverse. The multiverse is constructed as follows. In wedge holography, we have two Karch-Randall branes, and these branes are joined at the defect. The setup is mathematically consistent only if the bulk metric satisfies the Neumann boundary condition (NBC) on the branes. The geometry of the branes can be anti de-Sitter, de-Sitter, or flat space, depending upon the bulk metric. We showed that one can construct a setup of 2n Karch-Randall branes in wedge holography, and the bulk metric still satisfies NBC on the 2n branes. These branes are located at r = ±nρ. We can localize the gravity on these branes using braneworld holography [142, 143]. Therefore, we have 2n branes embedded in the bulk. The geometry of these branes can be anti de-Sitter or de-Sitter or flat space but not the mixture of any two. Hence, we have a multiverse that is made up of 2n gravitating systems. Due to transparent boundary conditions at the defect, various universes existing in the multiverse can communicate with each other. If we consider two multiverses, then there will be the communication of the universes in a specific multiverse but not between the two multiverses. This model applies to the Page curve of black holes with multiple horizons. We explicitly did this for Schwarzschild de-Sitter black hole and argued that we could get the Page curve of the SdS black hole by taking two copies of wedge holography so that one copy describes the Schwarzschild patch with flat space branes and the other copy describes the de-Sitter patch with two de-Sitter branes. By doing so obtained the Page curve of Schwarzschild and de-Sitter patches separately, similar to [12] and concluded that we couldn’t get the Page curve of SdS black hole with two Karch-Randall branes in wedge holography. Since the multiverse consists of communicating universes and hence one could avoid the “grandfather paradox” by not traveling to the universe in which one’s grandfather is living, similar to “many world theory”. In future, we shall work on the following issues: Future Outlook: • Using the doubly holographic setup constructed in chapter 7 from a top-down approach. We will compute the reflected entropy from the bulk point of view [245]. This will shed light on the holographic QCD via gauge-gravity duality. We are interested to see the effect of the O(R4) terms on the reflected entropy and how the higher derivative terms affect the physics of thermal QCD. • We will study the complexity growth of black holes with multiple horizons using the complexity equal volume [246] and complexity equals action proposals [247]. • In chapter 9, we saw that wedge holography is capable of describing the multiverse. The most interesting thing about this setup is that all the universes existing in the multiverse are capable of transferring information with each other. Using this feature, we provided a qualitative resolution of the “grandfather paradox”. We shall work on the more concrete resolution of the “grandfather paradox by providing a quantitative description of the “grandfather paradox” and its resolution. Further, using this setup, we will obtain the Page curve of the Reissner-Nordström de-Sitter black hole. This paper is under CC 4.0 license. available on arxiv

Thermal QCD Phenomenology at Intermediate Gauge/'t Hooft Coupling: Conclusion and Future Outlook

ইন্টারমিডিয়েট গেজ/'টি হুফ্ট কাপলিং এ থার্মাল কিউসিডি ফেনোমেনোলজি: উপসংহার এবং ভবিষ্যত আউটলুক

Thermische QCD-Phänomenologie bei Intermediate Gauge/'t Hooft-Kopplung: Schlussfolgerung und Zukunftsaussichten

Fenomenología térmica de QCD en el acoplamiento de calibre intermedio/'t Hooft: conclusión y perspectivas futuras

Phénoménologie QCD thermique au couplage jauge intermédiaire/'t Hooft : conclusion et perspectives d'avenir

इंटरमीडिएट गेज/टी हूफ्ट कपलिंग पर थर्मल क्यूसीडी फेनोमेनोलॉजी: निष्कर्ष और भविष्य का दृष्टिकोण

中間ゲージ/'t Hooftカップリングにおける熱QCD現象学：結論と将来の展望

중간 게이지/후프트 커플링의 열적 QCD 현상: 결론 및 향후 전망

Fenomenologia Térmica QCD no Acoplamento Intermediário Gauge/'t Hooft: Conclusão e Perspectivas Futuras

Феноменология термической КХД на промежуточной калибровке и связи Хоофта: заключение и перспективы на будущее

Orta Derecede/'t Toynak Bağlantısında Termal QCD Fenomenolojisi: Sonuç ve Geleceğe Bakış

Hiện tượng QCD nhiệt ở khớp nối trung gian/'t Hooft: Kết luận và triển vọng trong tương lai

中间规格/'t Hooft 耦合的热 QCD 现象学：结论和未来展望

Authors: (1) Gopal Yadav, Department of Physics, Indian Institute of Technology & Chennai Mathematical Institute. Table of Links Abstract Acknowledgment PART I Chapter 1: Introduction Chapter 2: SU(3) LECs from Type IIA String Theory Chapter 3: Deconfinement Phase Transition in Thermal QCD-Like Theories at Intermediate Coupling in the Absence and Presence of Rotation Chapter 4: Conclusion and Future Outlook PART II Chapter 5: Introduction Chapter 6: Page Curves of Reissner-Nordström Black Hole in HD Gravity Chapter 7: Entanglement Entropy and Page Curve from the M-Theory Dual of Thermal QCD Above Tc at Intermediate Coupling Chapter 8: Black Hole Islands in Multi-Event Horizon Space-Times Chapter 9: Multiverse in Karch-Randall Braneworld Chapter 10: Conclusion and Future outlook APPENDIX A APPENDIX B APPENDIX C Bibliography CHAPTER 4 - CONCLUSION AND FUTURE OUTLOOK We explored the intermediate coupling regime of thermal QCD-like theories from a top-down model constructed in [1]. The model is obtained as the extension of [15] by including higher derivative terms (O(R4 )) in the eleven dimensional supergravity action. We studied the following issues in the context of holographic thermal QCD at intermediate coupling. We discussed the deconfinement phase transition in thermal QCD from the semi-classical method and entanglement entropy point of view. The semi-classical method is based on the Hawking Page phase transition between thermal and black hole background on the gravity dual side. The procedure is to obtain the on-shell action densities of thermal and black hole backgrounds and equates these two at the UV cut-off. We obtained the deconfinement temperature of thermal QCD by equating the leading order terms. We observed the “UV-IR” mixing, “Flavor Memory” effect, and “non-renormalization of Tc”. Let us explain these effects in some detail. • Deconfinement Phase Transition in Thermal QCD-Like Theories at Intermediate Coupling: When we equated the on-shell action densities at the UV cut-off, then we obtained a relationship between the integration constants appearing in the black hole background along the compact part of the noncompact four cycle, which is part of the flavor D7-branes worldvolume and higher derivative correction to the thermal background along the M-theory circle. This is called “UV-IR mixing” in our setup. Since the aforementioned integration constants are associated with the flavor D7-branes of parent type IIB string dual and hence they have the information about the flavor branes in the M-theory uplift, which has no branes. This is interpreted as the “Flavor Memory” effect in our setup. UV-IR Mixing and Flavor Memory Effect: The deconfinement phase transition in thermal QCD corresponds to phase transitions between the entanglement entropies of connected and disconnected surfaces in the language of gauge-gravity duality. We showed that the deconfinement phase transition occurs at the critical value of the length of the interval chosen to compute the entanglement entropy. In this process, we found that entanglement entropies of connected and disconnected surfaces do not receive the O(R4 ) corrections, and hence Tc does not receive the same. This is known as the non-renormalization of the deconfinement temperature of thermal QCD-like theories. Non-Renormalization of Tc: While matching one of the one-loop renormalized LECs with the phenomenological data in [2], we imposed the constraint on the combination of integration constants mentioned earlier but now for the thermal background. The constraint was that one would get the exact matching with phenomenological data provided the combination, as mentioned above, should have a negative sign. In this paper, we explicitly calculated the expressions of integration constants for the thermal background and showed that the constraint is satisfied, and hence we showed the compatibility between our chiral perturbation theory study and deconfinement temperature computation. MχPT-Tc Compatibility: We constructed the holographic dual of rotating QGP by making one of the spatial coordinates in the M-theory dual periodic and performing the Lorentz transformation along the temporal and the periodic coordinate mentioned earlier. The gravity dual will be a rotating cylindrical black hole and thermal backgrounds when T > Tc and T < Tc on the thermal QCD side. Since the cylindrical black hole has the angular velocity, this maps to the angular velocity of rotation of QGP in thermal QCD via gauge-gravity duality. We followed the semi-classical method to study the deconfinement phase transition in rotating QGP from a top-down model. We found that the deconfinement temperature of thermal QCD is inversely proportional to the Lorentz factor, implying that as QGP rotation increases, Tc decreases and vice-versa. When we analyze the effect of higher derivative terms similar to [3], we found that one again observed “UV-IR mixing”, “Flavor Memory effect”, and “non-renormalization of Tc” even in the rotating QGP. In this paper, we showed the normalization of Tc by calculating the higher derivative correction to the Hawking temperature too. Since, Hawking temperature maps to Tc on the QCD side via Hawking-Page phase transition in the context of gauge-gravity duality. We found that Hawking temperature receives no higher derivative corrections, guaranteeing that Tc is non-renormalized. • Deconfinement Phase Transition in Rotating QGP at Intermediate Coupling: Future Physics outlook: • The LEC H1 of (2.1) and, in general, the LECs of the χPT Lagrangian at O(p 6 ) [124] may be calculated using the given values of the parameters of our M-theory dual of thermal QCD-like theories. This paper is under CC 4.0 license. available on arxiv

The Future of Thermal QCD Phenomenology at Intermediate Gauge/'t Hooft Coupling

Authors: (1) Gopal Yadav, Department of Physics, Indian Institute of Technology & Chennai Mathematical Institute. Table of Links Abstract Acknowledgment PART I Chapter 1: Introduction Chapter 2: SU(3) LECs from Type IIA String Theory Chapter 3: Deconfinement Phase Transition in Thermal QCD-Like Theories at Intermediate Coupling in the Absence and Presence of Rotation Chapter 4: Conclusion and Future Outlook PART II Chapter 5: Introduction Chapter 6: Page Curves of Reissner-Nordström Black Hole in HD Gravity Chapter 7: Entanglement Entropy and Page Curve from the M-Theory Dual of Thermal QCD Above Tc at Intermediate Coupling Chapter 8: Black Hole Islands in Multi-Event Horizon Space-Times Chapter 9: Multiverse in Karch-Randall Braneworld Chapter 10: Conclusion and Future outlook APPENDIX A APPENDIX B APPENDIX C Bibliography ACKNOWLEDGMENTS I am very grateful to my supervisor, Prof. Aalok Misra, for guiding me during my Ph.D. and making me what I am today. I enjoyed all the discussions that we have together. He trained me so that I can now do independent research. Apart from the research part, I learned many things from him, which helped me in the development of my personality in real life and as a researcher. I am very fortunate to have him as my supervisor. I am very thankful to my supervisor and his family, who always treated me like a family member, and for their encouragement, appreciation, and blessings. Without all these, my Ph.D. journey would not have been so smooth and pleasant. I would like to thank the very humble members of my research committee known as “Student Research Committee (SRC)”: Prof. Tashi Nautiyal (chairperson SRC), Prof. Dibakar Roychowdhury (internal member), Prof. Sugata Gangopadhyay (external member - Department of Computer Science and Engineering, I.I.T. Roorkee) and Prof. Arnab Kundu (Saha Institute of Nuclear Physics (SINP), Kolkata, India, an external member of me as a research fellow of CSIR), for their appreciation, encouragement, valuable comments, questions and evaluating me time to time. I am very grateful to Prof. Dibakar Roychowdhury for the discussions related to the research and post-doctoral position. He always encouraged me not to get tired and never give up. I would like to thank my collaborators, my supervisor, Dr. Vikas Yadav and Mr. Nitin Joshi (Indian Institute of Technology Ropar, Punjab, India) for working on the projects and publishing the papers with me. I would like to thank my colleagues from the string theory and high energy physics group Shivam, Hemant, Jitendra, Salman, Debarshi, Pushpa, Sumit and Abhishek for the valuable discussions, comments and questions. I am very grateful to the two former students from our research group Prof. Pramod Shukla (Bose Institute, Kolkata, India) and Dr. Karunva Sil (University of Cyprus) for their very helpful suggestions and guidance to me which helped me in getting a post-doctoral position. I am very grateful to Prof. Keshav Dasgupta for the help related to academia. I would like to thank Prof. Juan Maldacena (IAS, Princeton, USA), Prof. Andreas Karch (The University of Texas, Austin, USA), Prof. Tadashi Takayanagi (YITP, Kyoto University, Kyoto, Japan), Prof. Kostas Skenderis (University of Southampton, UK), Prof. Thomas Hartman (Cornell University), Prof. Suvrat Raju (ICTS, Bangalore), Prof. David Berenstein (University of California, Santa Barbara, USA), Prof. Xi Dong (University of California, Santa Barbara, USA), Prof. Arpan Bhattacharyya (IIT Gandhinagar, India), Prof. Christoph Uhlemann (University of Oxford), Prof. Rong-Xin Miao (Sun Yat-Sen University, China), Prof. Xuanhua Wang (UCAS, Wenzhou, China), Prof. Xian-Hui Ge (Shanghai University, China), Prof. Mohsen Alishahiha (IPM, Tehran, Iran), Prof. Sanjay Siwach (BHU, India), Prof. Chethan Krishnan (IISc Bangalore) for the useful discussions and comments during my PhD. I would also like to thank Prof. Suresh Tiwari, Prof. Rudra Prakash Malik, and Prof. Bhabani Prasad Mandal from the Banaras Hindu University (BHU), India, who helped me to start my journey into the Theoretical High Energy Physics during my master’s. I would also like to thank the editors, associate editors, and referees of the Journal of High Energy Physics (JHEP), Physical Review D (PRD), Physics Letters B (PLB), and European Physical Journal C (EPJC) for their comments, criticism, etc. Those comments helped me in learning something new which was missing in my papers. I am very grateful to the organizers (including speakers and participants) of the various conferences/workshops/schools for organizing very interesting events. I enjoyed those events and learned about the many new research topics. I would like to thank the members of Indian Physics Association (IPA) Roorkee chapter. I enjoyed working with them. The members include, Prof. Akhilesh Kumar Mishra, Prof. Anjani Kumar Tiwari, Ishani, Aalok, Jaikhomba, Nifeeya, Prem Sagar, Priyanshu, Ritika, Shikha, Tsewang, Vanshaj, Vidisha. I would like to extend my gratitude to all the faculty members, staff, and to students, and postdocs in the Department of Physics at I.I.T. Roorkee for making this a memorable journey. I would like to thank my colleagues from the : Shakti, Soumya, Monika, Amarjyoti, Sonu, Pooja, Pooja, Manish, Veer and Mukesh for bearing me and making the workplace vibrant. I also thank my colleagues from the all the research scholar rooms. I thank my friends Shailesh, Rahul, Anurag, Nandeshwar, Sarvesh, Amit, Ramnivas, Shubhajit for their time to time motivation and encouragement. research scholar room 2 I am very thankful to have wonderful seniors who treated me like younger brother: Shubham, Naveen, Aalok, Dibyendu. I specially thank Prem Sagar who took care of me always during my stay at IIT Roorkee and Deepak for the wonderful company. I would like to thank Priyanka, Pooja and Jaikhomba who helped in various way during pre-synopsis and thesis submission. I am very thankful to Anil, Ramashish, Amarjyoti, Shakti and Soumya for their real life knowledge, I feel everyone should have friends like them but please don’t follow them otherwise you may get bitten at some places. I am also thankful to Shivam and Shubranshu for their valuable time and discussion on the real life issues. It was a great pleasure to have Manish, Brij Mohan, Ashutosh, Arun, Harsh, Ishitwa, Shakti at IIT Roorkee who are the alumni from BHU. I thank my friends Divya, Pavneet, Ankur, Anshu, Hemant, Anju, Rahul, Ashish, Tejaswini, Gagan, Uwais for their valuable time and discussions (on various topics) during my stay at IITR. I am very grateful to my family for their continuous support and everything. I am very grateful to my parents (Shri Shyam Narayan Yadav and Shrimati Chinta Devi) who always left me free to do what I wanted to do. I was very fortunate to learn many things about life from my grandfather (Late Shri Ghurfekan Yadav). Seeing me as “Dr. Gopal Yadav” was his dream, I think he will be very happy for me wherever he will be now. I thank my maternal uncle and aunty, “Phupha” and “Bua”, and brother in laws who always encouraged me to believe in myself and for their support. I am very fortunate to have bhaiya and bhabhi, Rinki di, Priyanka di, Shaloo, Prity, Sandip, Arvind bhaiya, Santosh bhaiya, Ravi bhaiya, Bunty, Aman, Aditya, Mahesh, Vipul, Pooja, Ranjita di, Anjali, Akriti, Ankita, Shrija, Devansh, Shreya, Shivansh, Tejas in my life. I am very grateful to my school teachers, college/university professors, and all of my gurus in various fields for educating me in various aspects of life. Education can bring changes and what I am today is the perfect example of it. This paper is under CC 4.0 license. available on arxiv

Aspects of Thermal QCD Phenomenology at Intermediate Gauge/'t Hooft Coupling: Acknowledgment 

Authors: (1) Gopal Yadav, Department of Physics, Indian Institute of Technology & Chennai Mathematical Institute. Table of Links Abstract Acknowledgment PART I Chapter 1: Introduction Chapter 2: SU(3) LECs from Type IIA String Theory Chapter 3: Deconfinement Phase Transition in Thermal QCD-Like Theories at Intermediate Coupling in the Absence and Presence of Rotation Chapter 4: Conclusion and Future Outlook PART II Chapter 5: Introduction Chapter 6: Page Curves of Reissner-Nordström Black Hole in HD Gravity Chapter 7: Entanglement Entropy and Page Curve from the M-Theory Dual of Thermal QCD Above Tc at Intermediate Coupling Chapter 8: Black Hole Islands in Multi-Event Horizon Space-Times Chapter 9: Multiverse in Karch-Randall Braneworld Chapter 10: Conclusion and Future outlook APPENDIX A APPENDIX B APPENDIX C Bibliography Abstract The holographic dual of thermal QCD-like theories at intermediate coupling was constructed in [1] by including the O(R4 ) terms in the eleven-dimensional supergravity action. First part of the thesis explored the application of [1] and the following issues have been addressed in the first part of this thesis. In [2], we have computed the low energy coupling constants (LECs) of SU(3) chiral perturbation theory in the chiral limit from the type IIA string dual inclusive of O(R4 ) corrections. We matched our results with the phenomenological data and found the connection between higher derivative terms and large-N expansion. In [3], we computed the deconfinement temperature of thermal QCD-like theories at intermediate coupling from M theory dual inclusive of O(R4 ) corrections using Witten’s prescription [4] in the absence of rotation. In this process, we observed a novel “UV-IR” mixing, “Flavor Memory” effect (memory of flavor D7 branes considered in parent type IIB string dual was contained in the aforementioned no-braner M-theory uplift of large-N thermal QCD) and non-renormalization of deconfinement temperature (Tc) beyond one loop in the zero instanton sector from semiclassical computation and entanglement entropy points of view. We also discussed confinement-deconfinement phase transition in thermal QCDlike theories from the entanglement entropy point of view too, where the aforementioned sectors correspond to entanglement entropies of connected and disconnected RT surfaces in gravity dual. Further, we showed compatibility of the results obtained with MχPT as obtained in [2]. Then in [5], we constructed holographic dual of rotating quark-gluon plasma (QGP) by performing Lorentz transformations in the subspace of eleven-dimensional M theory metric on the gravity dual side. We computed the deconfinement temperature (Tc) of rotating QGP using semiclassical method [4] and found that the deconfinement temperature of rotating QGP is inversely proportional to Lorentz factor, which implies that it decreases when Tc increases and vice-versa. Further, “UV-IR” mixing, “nonrenormanization of Tc” and “Flavor Memory” effect were again observed in the holographic study of rotating QGP. From the applications of the island proposal [6], doubly holographic setup [7], and wedge holography [8, 9], we explored the following issues. In [10], we obtained the Page curves of Reissner-Nordström black hole in the presence of higher derivative terms (O(R2 )) in the gravitational action. We used the Island proposal [6] to do the same and found that Page curves are shifted towards later times or earlier times when Gauss-Bonnet coupling increases or decreases. Scrambling time is affected when we considered general O(R2 ) terms, whereas it was unaffected in Einstein-Maxwell-GaussBonnet gravity. Based on these results, one can say that the “dominance of the island” is affected by the presence of higher derivative terms. We obtained the Page curve of the Schwarzschild de-Sitter (SdS) black hole using the island proposal from a non-holographic approach in [12] for the black hole and de-Sitter patches separately. This was possible because of the insertion of thermal opaque membranes on both sides of the black hole and de-Sitter patches. We obtained the Page curve of the black hole patch by plotting the entanglement entropy of Hawking radiation in the absence and presence of the island surface. In the case of the SdS black hole, we found that island is located inside the black hole in contrast to the universal result that island is located outside the black hole. We also discussed that “dominance of islands” and “information recovery” takes more time for the low-temperature black hole patch compared to the high-temperature black hole patch. We described the Multiverse in [13] from the application of wedge holography. Multiverse is described as the setup of 2n anti de-Sitter (AdS) or de-Sitter branes embedded in the corresponding bulk. Due to different bulks for the AdS and de-Sitter branes, we can’t have the Multiverse made up of AdS and de-Sitter branes both. Since all the universes can communicate with each other due to transparent boundary conditions at the defect, one could resolve the “grandfather paradox” in this setup. This setup is also used to obtain the Page curve of the Schwarzschild de-Sitter black hole, which has two horizons. This paper is under CC 4.0 license. available on arxiv

Aspects of Thermal QCD Phenomenology at Intermediate Gauge/'t Hooft Coupling

The Future of Education and AI: Beyond Traditional Degrees with Marc Andreessen & Ben Horowitz

শিক্ষার ভবিষ্যত এবং এআই: মার্ক অ্যান্ড্রেসেন এবং বেন হোরোভিটজের সাথে ঐতিহ্যগত ডিগ্রির বাইরে

Die Zukunft von Bildung und KI: Jenseits traditioneller Abschlüsse mit Marc Andreessen und Ben Horowitz

El futuro de la educación y la IA: más allá de las titulaciones tradicionales con Marc Andreessen y Ben Horowitz

L'avenir de l'éducation et de l'IA : au-delà des diplômes traditionnels avec Marc Andreessen et Ben Horowitz

शिक्षा और एआई का भविष्य: मार्क आंद्रेसेन और बेन होरोविट्ज़ के साथ पारंपरिक डिग्री से परे

教育と AI の未来: マーク・アンドリーセンとベン・ホロウィッツによる従来の学位を超えて

교육과 AI의 미래: Marc Andreessen 및 Ben Horowitz와 함께하는 전통적인 학위를 넘어서

O futuro da educação e da IA: além dos diplomas tradicionais com Marc Andreessen e Ben Horowitz

Будущее образования и искусственного интеллекта: за пределами традиционных степеней с Марком Андриссеном и Беном Горовицем

Eğitimin ve Yapay Zekanın Geleceği: Marc Andreessen ve Ben Horowitz ile Geleneksel Derecelerin Ötesinde

Tương lai của Giáo dục và AI: Vượt xa các bằng cấp truyền thống với Marc Andreessen & Ben Horowitz

教育和人工智能的未来：马克·安德森 (Marc Andreessen) 和本·霍洛维茨 (Ben Horowitz) 的超越传统学位

If you have ever worked on a Spring application using Hibernate 5, you probably encountered the challenge of dealing with duplicated entities. It is an odd scenario where your collection contains multiple entries referencing the same entity. This is a quite known issue, and there are ways to address it whether using the keyword, Sets, or JPA EntityGraph. DISTINCT However, I happened to have quite disturbing behavior using EntityGraph returning duplicated entities! We will be diving a bit under the hood of Hibernate 5 to understand what happened. A Simple Spring Boot Application To illustrate Hibernate 5 behavior, let’s start with a basic Spring Boot project connected to a database: https://github.com/Shaolans/HibernateEntityGraphDeduplicationIssue The database schema is a simple model as follows: The Hibernate entities are defined as follows: Our focus will be on the queries generated by this JPA repository: @Repository
public interface AuthorRepository extends JpaRepository<Author, Integer> {

    @Query("SELECT a FROM Author a LEFT JOIN FETCH a.books")
    List<Author> findAuthorsLeftJoinFetchNoEntityGraph();

    @EntityGraph(attributePaths = "books")
    @Query("FROM Author a LEFT JOIN a.books")
    List<Author> findAuthorsLeftJoinWithEntityGraph();

    @Query("FROM Author a LEFT JOIN a.books")
    List<Author> findAuthorsLeftJoinWithoutEntityGraph();

    @EntityGraph(attributePaths = "books")
    @Query("FROM Author a INNER JOIN a.agent WHERE a.agent.name like '%John%'")
    List<Author> findAuthorsWithJoinNotFetchedAndEntityGraph();

    @EntityGraph(attributePaths = "books")
    @Query("SELECT a FROM Author a INNER JOIN a.agent WHERE a.agent.name like '%John%'")
    List<Author> findAuthorsWithJoinNotFetchedAndEntityGraphAndSelect();
} Entity Duplication Why Does It Happen? To understand the occurrence of entity duplication, let’s consider a use case where the objective is to retrieve all authors and their respective books. In order to avoid the issue I include in my JPQL query the keyword . N+1 query FETCH It enables the retrieval of both authors and their associated books in a single SQL query, eliminating the necessity to individually fetch books for each author. @Query("SELECT a FROM Author a LEFT JOIN FETCH a.books")
List<Author> findAuthorsLeftJoinFetchNoEntityGraph(); Invoking this method will result in the compilation of an SQL query equivalent to the following: SELECT A, B FROM AUTHOR A LEFT JOIN BOOK B ON A.ID = B.BOOK_AUTHOR_ID; In a case where you have 2 authors that have respectively 2 and 3 books, the result of the SQL query will yield the following table: Depending on the type of used, the association between the and tables are established based on the provided condition. join Author Book This will produce for each that matched an , a new row containing the columns of the table but also the columns of the table. Book Author Book Author Hibernate, upon retrieving this result set, intelligently resolves the entity without duplication. In our case, we end up with only two instances of the entity. However, it handles resolution on a row-by-row basis and does not inherently deduplicate the rows by default. Author This explains why the , returned by calling , returns the following collection: List findAuthorsLeftJoinFetchNoEntityGraph [Author@5640, Author@5640, Author@5641, Author@5641, Author@5641] being the instance representing J.R.R Tolkien entity and representing the Isaac Asimov. Author@5640 Author Author@5641 Author This duplication is mostly observed on and relationships since joining with these types of relations might match multiple rows of the associated table. @OneToMany @ManyToMany On the contrary, and relationships match at most only 1 entry on the associated table and will not induce duplication. @OneToOne @ManyToOne How to Deduplicate Although this duplication issue is quite common and often occurs during the development of applications, there are ways to address and resolve this issue. Set A straightforward solution involves using the returning type instead of : Set<Author> List<Author> @Query("FROM Author a LEFT JOIN FETCH a.books")
Set<Author> findAuthorsLeftJoinFetchNoEntityGraph(); When the results are collected, duplicated entities will be filtered through the . Set DISTINCT keyword Another approach is to use the keyword: DISTINCT @Query("SELECT DISTINCT a FROM Author a LEFT JOIN FETCH a.books")
List<Author> findAuthorsLeftJoinFetchNoEntityGraph(); It should be noted that using as two semantic meanings: DISTINCT : The conventional SQL meaning involves filtering duplicate values in the selected columns. SQL : It indicates a desire to filter duplications in the parent entity. Hibernate When the keyword is used in a JPQL query, it leads to the generation of an SQL query featuring the keyword but also instructing Hibernate to filter duplicated entities. DISTINCT DISTINCT However, using in SQL induces an overhead when executed in the database, and in some cases, the goal is to only filter duplicate entities induced by the join. For such cases, the Hibernate hint can be employed to avoid the generation of in the SQL query: DISTINCT HINT_PASS_DISTINCT_THROUGH DISTINCT @QueryHints(@QueryHint(name = HINT_PASS_DISTINCT_THROUGH, value = "false"))
@Query("SELECT DISTINCT a FROM Author a LEFT JOIN FETCH a.books")
Set<Author> findDistinctAuthorsLeftJoinFetchNoEntityGraph(); EntityGraph In JPA 2.1, EntityGraph was introduced as a powerful feature allowing developers to define the loading strategies of entities. In our case, we can just use the annotation to load the books along with the , as illustrated below: @EntityGraph Author @EntityGraph(attributePaths = "books")
@Query("FROM Author a LEFT JOIN a.books WHERE a.books.size > 2")
List<Author> findAuthorsLeftJoinWithEntityGraph(); This JPQL query is designed to retrieve all authors, along with their respective books, who possess more than 2 books. Even without explicitly including the keyword in the SQL query, the EntityGraph ensures the books are loaded and the parent entity remains non-duplicated. FETCH Author : This is a simple example of using EntityGraph; a more complete and sophisticated way of using it exists, but this is not the scope of this section. Note EntityGraph and Entity Duplication While it is established that EntityGraph handles entity deduplication, let's look into a more complicated scenario. Consider the entity, which has a relation with . Suppose the objective is to retrieve all authors and their books where the author's agent has a name containing "John", yet we have no intention of loading the entity for an arbitrary reason. In this case, we can accomplish this by the following code: Author @ManyToOne Agent Agent @EntityGraph(attributePaths = "books")
@Query("FROM Author a INNER JOIN a.agent WHERE a.agent.name like '%John%'")
List<Author> findAuthorsWithJoinNotFetchedAndEntityGraph(); Since we are using EntityGraph, we expect to avoid duplicated , but upon executing the method, the outcome is unexpected: Author Duplicated entities are retrieved despite the use of EntityGraph. To understand the underlying reasons for this behavior, let’s dive a bit under the hood of Hibernate! How Hibernate Resolves Entity Duplication Hibernate is a quite complete and complex ORM, it can be hard to grasp entirely its fine details, but in our case, since we want to understand deduplication mechanisms, we will be focusing on the method of list . QueryTranslatorImpl For the sake of clarity, some portions of the code have been omitted in order to highlight the most crucial aspects. Upon invoking a method from the , the execution will eventually reach this code snippet. Here is a breakdown of its functionality: AuthorRepository It computes a boolean called , and as the name implies, it identifies whether the result set needs to be deduplicated. needsDistincting We can observe when we do use a keyword, EntityGraph, or limit the size of retrieval, there is a operation in the JPQL query; the distinction needs to be applied. DISTINCT AND FETCH In our issue, it can be observed that whenever EntityGraph is used, the distinction will be applied since EntityGraph will edit the source query to “ ” child entities given in the attribute paths. FETCH This method invocation executes the query in the database, retrieves the result set, and resolves the entities. This list might contain duplicated entities. This is the most interesting part here; when it does need to distinguish entities, Hibernate uses an to filter out the duplicated entity. IdentitySet At this point, it is established that using EntityGraph should filter duplicated entities, but what happened to cause the unexpected outcome previously discussed? Why EntityGraph Returns Duplicates in Some Cases Let’s Compare In order to have a better understanding of the situation, let’s compare the results of when invoking the following methods: queryLoader.list( session, queryParametersToUse ) (2) @EntityGraph(attributePaths = "books")
@Query("FROM Author a LEFT JOIN a.books")
List<Author> findAuthorsLeftJoinWithEntityGraph(); and @EntityGraph(attributePaths = "books")
@Query("FROM Author a INNER JOIN a.agent WHERE a.agent.name like '%John%'")
List<Author> findAuthorsWithJoinNotFetchedAndEntityGraph(); Upon calling , the returned results contains: findAuthorsLeftJoinWithEntityGraph Given the EntityGraph is used, the duplication will be resolved through the , and at the end, the method will return a consisting of 3 authors/instances. IdentitySet List<Author> However, upon calling , the returned results contains the following: findAuthorsWithJoinNotFetchedAndEntityGraph In this scenario, the result is not a List of instances but rather a of distinct array instances of Objects; each encapsulating duplicated and instances. The reason behind the presence of duplicate entities becomes evident. Author List Author Agent Each array ( , , ..., ), being a unique instance, is not filtered during the distinction process with the . Object[2]@13551 Object[2]@135512 Object[2]@13555 IdentitySet Consequently, all arrays are considered as distinct instances, leading to the observed duplication. Explaining the Difference In order to understand the difference between obtaining a List of instances in the former case and a list of arrays containing and instances in the latter case, we need to explore deeper; let’s take a look at the class and especially the method . Author Author Agent QueryLoader initialize This initialization code has interesting parts, particularly the one highlighted in red. It creates an array of boolean where it checks which entities should be selected and be returned. includeInSelect Let’s take for example: @Query("SELECT a, b FROM Author a LEFT JOIN FETCH a.books b") The initialize method checks the content one by one which is and ; if the selected entity originates from a in the clause, then it will be omitted since is used to load children entities (but not in the case of the parent entity). Otherwise, the entity should be selected. SELECT a b FETCH FROM FETCH In this example, the array contains . includeInSelect [true (Author), false (Book)] In our case, of entity duplication with EntityGraph: @EntityGraph(attributePaths = "books")
@Query("FROM Author a INNER JOIN a.agent WHERE a.agent.name like 'John'")
List<Author> findAuthorsWithJoinNotFetchedAndEntityGraph(); We did not specify the clause, so by default, it will select all the entities from all the tables specified in the clause. SELECT FROM The logic returns an array where and (2 elements) should be selected because only is subject to a operation due to the use of EntityGraph. includeInSelect [true (Author), false (Book), true (Agent)] Author Agent Book FETCH This explains the difference between and . findAuthorsLeftJoinWithEntityGraph findAuthorsWithJoinNotFetchedAndEntityGraph The former returns only one value per row because the clause contained only and entities (the select of was generated by EntityGraph), however, since was subject to a , it was not taken into account in the . SELECT Author Book Book Book FETCH includeInSelect The latter returns an array per row because and were in the clause and are not subject to a operation unlike . Thus, returning an array consisting of 2 elements per row. Author Agent SELECT FETCH Book In summary, Hibernate consistently returns an array, and the content of this array is determined by the entities specified in the clause that are not associated with operations. SELECT FETCH However, if we follow the preceding logic, should also return an array but an array of a single element. This is accurate; it does. However, upon examining the implementation at ** **lines and , when the array consists of a single element, the element is just unwrapped. findAuthorsLeftJoinWithEntityGraph QueryLoader 476 620 How to Fix It To ensure correct duplicate filtering when applying a distinction, the result set should be a list of entities rather than a list of entity arrays. This behavior is determined by the entities selected. A straightforward solution is to include the desired entities in the clause: SELECT @EntityGraph(attributePaths = "books")
@Query("SELECT a FROM Author a INNER JOIN a.agent WHERE a.agent.name like '%John%'")
List<Author> findAuthorsWithJoinNotFetchedAndEntityGraph(); The clause will only contain and (the select being generated by the EntityGraph): SELECT Author Book Book Since is a operation, the will only select one element ( ), and instead of returning an array, it will return directly the instance which then will pass through the to be deduplicated. Book FETCH includeInSelect Author Author IdentitySet Conclusion Entity duplication occurs when tables are joined, and multiple rows are matched. There are several methods to address this issue, including using , the keyword, or EntityGraph to deduplicate the result set. Set DISTINCT In the last two cases, deduplication is achieved through a Hibernate flag that accumulates results into an . IdentitySet However, it may not work in certain scenarios due to the fact that, depending on your clause, it could return newly instantiated arrays of your selected entities for each row. This could undermine deduplication through the . SELECT IdentitySet Therefore, it is advisable, when writing JPQL queries, to always specify the clause. If not supplied, all entities in the clause that are not subject to a operation will be selected by default. SELECT FROM FETCH The issue of duplicated parent entities is addressed in Hibernate 6 (shipped in Spring Boot 3), as it has introduced automatic handling of duplicated entities. However, considering that the release of Hibernate 6 is relatively recent, many applications still run on Hibernate 5 or earlier versions, and migration from Hibernate 5 to 6 might be challenging. Thus, understanding how Hibernate 5 handles these situations remains relevant for the considerable number of applications still using it. Also published here

Hibernate 5 and Entities Duplication: Let’s Dive Under the Hood

I just had an amazing discussion with , CEO of Holo Art, where art, science, technology, space, and consciousness converge. In this one, receiving an impressive artist, I took the opportunity to explore the intersection of technology and creativity: AI in the realm of art. Mariam shared her deep insights into how AI is not just augmenting but fundamentally transforming artistic expression. Mariam Brian We start discussing the revolutionary ways AI is being integrated into the artistic processes. From algorithms that can mimic classical painting techniques to those creating entirely new forms of visual expression. She emphasizes that AI isn't replacing artists but rather evolving as a collaborative tool that enhances human creativity and she . invites all artists, philosophers, and … well, all humans to play and experiment with AI A significant part of our discussion revolves around the ethical implications of AI in art. Mariam addresses concerns about originality and authorship, stressing the importance of a harmonious balance between human intuition and AI's capabilities. She shares cool and applied examples of AI-assisted projects where artists used algorithms as partners in their creative journey, resulting in artworks that are both technically innovative and emotionally resonant. You can also explore more on the , if interested. Holo Art website One of the highlights of the episode is when Mariam discusses the future of AI in art. She envisions a world where AI not only assists in creating art but also helps understand and interpret it, potentially opening new avenues for appreciating art across different cultures and perspectives. This episode is not just for art enthusiasts or AI enthusiasts. It is for anyone intrigued by the constantly changing relationship between humans and technology. Mariam's perspective is really interesting and optimistic with AI as a force for good in the creative world, challenging us to rethink our definitions of art and creativity. This episode will give you both hope and excitement for what’s to come with new technologies! Hear more of Mariam's expert artist insights in this episode of the What’s AI podcast with me, Louis-François Bouchard. Watch it now on , or listen to it on or : YouTube Spotify Apple Podcasts https://youtu.be/yRFUY4XCSN0?embedable=true&transcript=true

Art in the Age of AI: Mariam Brian's Pioneering Vision for Holo Art

If you need to run operations before completing a Git commit, you can rely on Git Hooks. Git hooks are scripts that run automatically whenever a particular event occurs in a Git repository. They let you customize Git’s internal behaviour and trigger customizable actions at key points in the development life cycle. Extending Git hooks allows you to plug in to the regular Git flow, such as Git , , etc. custom functionalities message validation code formatting I’ve already described how to use , but here I’m gonna use , the version of Husky created for .NET-based applications. Husky with NPM Husky.NET Git hooks: a way to extend Git operations As we said, Git hooks are actions that run during specific phases of Git operations. Git hooks fall into : 4 categories : they execute when you run on your local repository; client-side hooks related to the committing workflow git commit : they are executed when running , which is a command that allows you to integrate mails and Git repositories (I’ve never used it. If you are interested in this functionality, ); client-side hooks related to the email workflow git am here’s the official documentation : these hooks run on your local repository when performing operations like ; client-side hooks related to other operations git rebase : they run after a commit is received on the remote repository, and they can reject a operation. server-side hooks git push Let’s focus on the client-side hooks that run when you commit changes using . git commit How to install Husky.NET and its dependencies in a .NET Application Husky.NET must be installed in the of the solution. root folder You first have to by running: create a file in the root folder tool-manifest dotnet new tool-manifest This command creates a file named under the folder: here, you can see the list of external tools used by dotnet. dotnet-tools.json .config After running the command, you will see that the file contains this element: dotnet-tools.json {
  "version": 1,
  "isRoot": true,
  "tools": {}
} Now you can by running: add Husky as a dotnet tool dotnet tool install Husky After running the command, the file will contain something like this: {
  "version": 1,
  "isRoot": true,
  "tools": {
    "husky": {
      "version": "0.6.2",
      "commands": ["husky"]
    }
  }
} Now that we have added it to our dependencies, we can by running: add Husky to an existing .NET application dotnet husky install If you open the root folder, you should be able to see these 3 folders: , which contains the info about the Git repository; .git that contains the description of the tools, such as ; .config dotnet-tools that contains the files we are going to use to define our Git hooks. .husky Finally, you can by running, for example, add a new hook dotnet husky add pre-commit -c "echo 'Hello world!'"
git add .husky/pre-commit This command creates a new file, (without file extension), under the folder. By default, it appears like this: pre-commit .husky #!/bin/sh
. "$(dirname "$0")/_/husky.sh"

## husky task runner examples -------------------
## Note : for local installation use 'dotnet' prefix. e.g. 'dotnet husky'

## run all tasks
#husky run

### run all tasks with group: 'group-name'
#husky run --group group-name

## run task with name: 'task-name'
#husky run --name task-name

## pass hook arguments to task
#husky run --args "$1" "$2"

## or put your custom commands -------------------
#echo 'Husky.Net is awesome!'

echo 'Hello world!' The default content is pretty useless; it’s time to customize that hook. Notice that the latest command has also generated a file; we will use it later. task-runner.json Your first pre-commit hook To customize the script, . open the file located at .husky/pre-commit Here, you can add whatever you want. In the example below, I run commands that compile the code, format the text (using with the rules defined in the .editorconfig file), and then run all the tests. dotnet format #!/bin/sh
. "$(dirname "$0")/_/husky.sh"

echo 'Building code'
dotnet build

echo 'Formatting code'
dotnet format

echo 'Running tests'
dotnet test Then, add it to Git, and you are ready to go. 🚀 But wait… 3 ways to manage dotnet format with Husky.NET There is a problem with the approach in the example above. Let’s simulate a usage flow: you modify a C# class; you run ; git commit -m "message" the pre-commit hook runs ; dotnet build the pre-commit hook runs ; dotnet format the pre-commit hook runs ; dotnet test after the hooks, the commit is created. What is the final result? Since modifies the source files, and given that the snapshot has already been created before executing the hook, all ! dotnet format the modified files will not be part of the final commit Also, executes linting on every file in the solution, not only those that are part of the current snapshot. The operation might then take a lot of time, depending on the size of the repository, and most of the time, it will not update any file (because you’ve already formatted everything in a previous run). dotnet format We have to work out a way to fix this issue. I’ll suggest three approaches. Include all the changes using Git add The first approach is quite simple: after . run git add . dotnet format So, the flow becomes: you modify a C# class; you run ; git commit -m "message" the pre-commit hook runs ; dotnet build the pre-commit hook runs ; dotnet format the pre-commit hook runs ; git add . the pre-commit hook runs ; dotnet test Git creates the commit. This is the most straightforward approach, but it has some downsides: is executed on every file in the solution. The more your project grows, the slower your commits become; dotnet format adds to the current snapshot all the files modified, even those you did not add to this commit on purpose (maybe because you have updated many files and want to create two distinct commits). git add . So, it works, but we can do better. Execute a dry run of dotnet-format You can to the command: this flag returns an error if at least one file needs to be updated because of a formatting rule. add the --verify-no-changes dotnet format Let’s see how the flow changes if one file needs to be formatted. you modify a C# class; you run ; git commit -m "message" the pre-commit hook runs ; dotnet build the pre-commit hook runs ; dotnet format --verify-no-changes the pre-commit hook returns an error and aborts the operation; run on the whole solution to fix all the formatting issues; you dotnet format you run ; git add . you run ; git commit -m "message" the pre-commit hook runs ; dotnet build the pre-commit hook runs . Now, there is nothing to format, and we can proceed; dotnet format --verify-no-changes the pre-commit hook runs ; dotnet test Git creates the commit. Notice that, this way, if there is something to format, the whole commit is aborted. You will then have to run on the entire solution, fix the errors, add the changes to the snapshot, and restart the flow. dotnet format It’s a longer process, but it allows you to have complete control over the formatted files. Also, you won’t risk including in the snapshot the files you want to keep staged in order to add them to a subsequent commit. Run dotnet-format only on the staged files using Husky.NET Task Runner The third approach is the most complex but with the best result. If you recall, during the initialization, Husky added two files in the folder: and . .husky pre-commit task-runner.json The key to this solution is the file. This file allows you to . task-runner.json create custom scripts with a name, a group, the command to be executed, and its related parameters By default, you will see this content: {
  "tasks": [
    {
      "name": "welcome-message-example",
      "command": "bash",
      "args": ["-c", "echo Husky.Net is awesome!"],
      "windows": {
        "command": "cmd",
        "args": ["/c", "echo Husky.Net is awesome!"]
      }
    }
  ]
} To make sure that runs only on the staged files, you must like this: dotnet format create a new task {
  "name": "dotnet-format-staged-files",
  "group": "pre-commit-operations",
  "command": "dotnet",
  "args": ["format", "--include", "${staged}"],
  "include": ["**/*.cs"]
} Here, we have specified a name, , the command to run, , with some parameters listed in the array. Notice that parameter, which is populated by Husky.NET. dotnet-format-staged-files dotnet args we can filter the list of files to be formatted by using the ${staged} We have also added this task to a named that we can use to reference a list of tasks to be executed together. group pre-commit-operations If you want to run a specific task, you can use . In our example, the command would be . dotnet husky run --name taskname dotnet husky run --name dotnet-format-staged-files If you want to run a set of tasks belonging to the same group, you can run . In our example, the command would be . dotnet husky run --group groupname dotnet husky run --group pre-commit-operations The last step is to call these tasks from within our file. So, replace the old command with one of the above commands. pre-commit dotnet format Final result and optimizations of the pre-commit hook Now that everything is in place, we can improve the script to make it faster. Let’s see which parts we can optimize. The first step is the . For sure, we have to run to see if the project builds correctly. You can consider adding the flag to skip the step before building. build phase dotnet build --no-restore restore Then we have the : we can avoid formatting every file using one of the steps defined before. I’ll replace the plain with the execution of the script defined in the Task Runner (it’s the third approach we saw). format phase dotnet format Then, we have the . We can add both the and the flag to the command since we have already built everything before. ! The format phase updated the content of our files, so we still have to build the whole solution. Unless we swap the and the phases. test phase --no-restore --no-build But wait build format So, here we have the final file: pre-commit #!/bin/sh
. "$(dirname "$0")/_/husky.sh"

echo 'Ready to commit changes!'

echo 'Format'

dotnet husky run --name dotnet-format-staged-files

echo 'Build'

dotnet build --no-restore

echo 'Test'

dotnet test --no-restore

echo 'Completed pre-commit changes' Yes, I know that when you run the command, you also build the solution, but I prefer having two separate steps just for clarity! dotnet test Ah, and at the beginning of the script! don’t remove the #!/bin/sh How to skip Git hooks To trigger the hook, just run . completing the commit, the hook will run all the commands. . git commit -m "message" Before If one of them fails, the whole commit operation is aborted There are cases when you have to . For example, if you have integration tests that rely on an external source currently offline. In that case, some tests will fail, and you will be able to commit your code only once the external system gets working again. skip the validation You can skip the commit validation by adding the flag: --no-verify git commit -m "my message" --no-verify Further readings Husky.NET is a porting of the Husky tool we already used in a previous article, using it as an NPM dependency. In that article, we also learned how to customize Conventional Commits using Git hooks. 🔗 How to customize Conventional Commits in a .NET application using GitHooks | Code4IT As we learned, there are many more Git hooks that we can use. You can see the complete list on the Git documentation: 🔗 Customizing Git - Git Hooks | Git docs Of course, if you want to get the best out of Husky.NET, I suggest you have a look at the official documentation: 🔗 Husky.Net documentation One last thing: we installed Husky.NET using dotnet tools. If you want to learn more about this topic, I found an excellent article online that you might want to read: 🔗 Using dotnet tools | Gustav Ehrenborg Wrapping up In this article, we learned how to create a Git hook and validate all our changes before committing them to our Git repository. pre-commit We also focused on the formatting of our code: how can we format only the files we have changed without impacting the whole solution? I hope you enjoyed this article! Let’s keep in touch on or ! 🤜🤛 Twitter LinkedIn Happy coding! 🐧 Also published . here

Optimizing .NET Development Workflow with Git Hooks and Husky.NET

In this guide, you will see how to handle hover events, one of the most common user interactions in web apps. onHover in React The library does not have built-in event, but there is a way to handle hovering events in React. onHover To implement this feature, you need two event handlers - to handle the when the mouse enters borders of the element, and to handle when the mouse leaves. Handling these two events ensures that hover event handler works consistently. onMouseEnter onMouseLeave Now let’s explore potential use-cases for onHover in React. In our first example, let’s set and handlers to show or hide a component when user hovers over the element. onMouseEnter onMouseLeave function App() {
  const [hidden, setHidden] = useState(true);
  return (
    <div
      className="container"
      onMouseEnter={() => setHidden(false)}
      onMouseLeave={() => setHidden(true)}
    >
      {hidden ? null : <h1>Hovering</h1>}
    </div>
  );
} In this example, we have a state variable , and its value is a boolean. Inside JSX, we look at the boolean value to conditionally render a header that says ‘Hovering’. hidden and event handlers are set on a div. event sets to , so the header text appears. sets it to , so when the mouse leaves the , the header text hides again. onMouseEnter onMouseLeave onMouseEnter hidden false onMouseLeave true div Here’s a to illustrate how and can replicate an event handler in React. live demo onMouseEnter onMouseLeave onHover - As you can see, the hovering effect activates even if your mouse is on the element’s border. If you liked this guide, SimpleFrontEnd blog has many similar with examples. React guides onHover to Conditionally Style Elements in React Similar to conditional rendering, you canuse and event handlers to conditionally style elements in React. onMouseEnter onMouseLeave To be more specific, event handlers update the state, which we can use to conditionally apply styles in JSX. function App() {
  const [warning, setWarning] = useState(true);
  return (
    <div
      className="container"
      onMouseEnter={() => setWarning(false)}
      onMouseLeave={() => setWarning(true)}
    >
      <h1 style={{ color: warning ? "goldenrod" : "green" }}>
        Please hover over the container{" "}
      </h1>
    </div>
  );
} In this example, and event handlers update state variable. Which we use to change color of the text in the container. onMouseEnter onMouseLeave warning You can also think of this as a programmatic alternative to using the :hover selector in CSS.

How to Handle Hover Events in React

A Complete Guide to React Hooks

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