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: "optimal coalition structures in graph games"
  Abstract: We consider the problem of finding the optimal coalition structure in \emph{Weighted Graph Games (WGGs)}, a simple restricted representation of coalitional games [Deng, Papadimitriou, Math. OR 1994]. The agents in such games are vertices of the graph, and the value of a coalition is the sum of the weights of the edges present between coalition members. The \emph{optimal coalition structure} is a partition of the agents to coalitions, that maximizes the sum of utilities obtained by the coalitions. We show that finding the optimal coalition structure is not only hard for general graphs, but is also intractable for restricted families such as planar graphs which are amenable for many other combinatorial problems. We then provide algorithms with constant factor approximations for planar, minor-free and bounded degree graphs.

Connected through hyperedge HE-1 (induced by source paper "next generation multicuts for semi planar graphs"):
  with members:
    - "fast planar correlation clustering for image segmentation"
    - "tightening lp relaxations for map using message passing"
    - "efficiently searching for frustrated cycles in map inference"
    - "large scale correlation clustering optimization"

Connected through hyperedge HE-2 (induced by source paper "planar ultrametric rounding for image segmentation"):
  with members:
    - "fast planar correlation clustering for image segmentation"
    - "large scale correlation clustering optimization"

Connected through hyperedge HE-3 (induced by source paper "fast planar correlation clustering for image segmentation"):
  with members:
    - "tightening lp relaxations for map using message passing"
    - "optimal coalition structures in cooperative graph games"
    - "efficient exact inference in planar ising models"

Connected through hyperedge HE-4 (induced by source paper "coalition structure generation over graphs"):
  with members:
    - "complexity of coalition structure generation"
    - "an anytime algorithm for optimal coalition structure generation"

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.GT(Computer Science and Game Theory)