human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "a comparison of the performance and scalability of relational and document based web systems for large scale applications in a rehabilitation context"
  Abstract: Background: The Virtual Rehabilitation Environment (VRE) provides patients of long term neurological conditions with a platform to review their previous physiotherapy sessions, as well as see their goals and any treatments or exercises that their clinician has set for them to practice before their next session. #R##N#Objective: The initial application implemented 21 of the 27 core features using the Microsoft ASP.NET MVC stack. However, the two core, non-functional requirements were negated from the project due to lack of experience and strict time constraints. This project aimed to investigate whether the application would be more suited to a non-relational solution. #R##N#Method: The application was re-written using the MEAN stack (MongoDB, ExpressJS, AngularJS, NodeJS), an open source, fully JavaScript stack and then performance tests were carried out to compare the two applications. A scalability review was also conducted to assess the benefits and drawbacks of each technology in this aspect. #R##N#Results: The investigation proved that the non-relational solution was much more efficient and performed faster. However, the choice of database was only a small part of the increase in efficiency and it was an all-round better design that gave the new application its performance upper hand. #R##N#Conclusion: A proposal for a new application design is given that follows the microservice architecture used by companies such as Amazon and Netflix. The application is to be split up into four parts; database, client application, server application and content delivery network. These four, independently scalable and manageable services offer the greatest flexibility for future development at the low costs necessary for a start-up.

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.CY(Computers and Society)