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: "structure of optimal cache placement for coded caching with heterogeneous demands"
  Abstract: For a caching system of a service provider and multiple cache-enabled users, we investigate the optimal cache placement for the coded caching scheme (CCS) under heterogeneous file demands. Existing works propose heuristic file grouping strategies, leading to suboptimal cache placements. We formulate the cache placement problem for the CCS into an optimization problem to minimize the average rate, for any file popularity distributions and cache size. Through problem reformulation and by exploring the properties of the problem, we obtain the structure of the optimal cache placement. We discover that the optimal cache placement results in at most three file groups. Through analysis, we present the complete structure of the optimal cache placement under each possible file group case and derive a closed-form cache placement solution in each of these cases. Following these results, the optimal cache placement solution can be obtained efficiently. Simulation verifies the optimal cache placement structure and solution, and provides a comparison to existing strategies.

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.IT(Information Theory)