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: "the hairy ball problem is ppad complete"
  Abstract: The Hairy Ball Theorem states that every continuous tangent vector field on an even-dimensional sphere must have a zero. We prove that the associated computational problem of computing an approximate zero is PPAD-complete. We also give a FIXP-hardness result for the general exact computation problem. #R##N#In order to show that this problem lies in PPAD, we provide new results on multiple-source variants of END-OF-LINE, the canonical PPAD-complete problem. In particular, finding an approximate zero of a Hairy Ball vector field on an even-dimensional sphere reduces to a 2-source END-OF-LINE problem. If the domain is changed to be the torus of genus $g \geq 2$ instead (where the Hairy Ball Theorem also holds), then the problem reduces to a $2(g-1)$-source END-OF-LINE problem. #R##N#These multiple-source END-OF-LINE results are of independent interest and provide new tools for showing membership in PPAD. In particular, we use them to provide the first full proof of PPAD-completeness for the IMBALANCE problem defined by Beame et al. in 1998.

Connected through hyperedge HE-1 (induced by source paper "consenus halving does it ever get easier"):
  with members:
    - "computing exact solutions of consensus halving and the borsuk ulam theorem"
    - "on the complexity of modulo q arguments and the chevalley warning theorem"
    - "fair and efficient cake division with connected pieces"
    - "the classes ppa k existence from arguments modulo k"
    - "the complexity of splitting necklaces and bisecting ham sandwiches"
    - "consensus halving is ppa complete"
    - "a discrete and bounded envy free cake cutting protocol for any number of agents"
    - "hardness results for consensus halving"

Connected through hyperedge HE-2 (induced by source paper "the classes ppa k existence from arguments modulo k"):
  with members:
    - "the complexity of splitting necklaces and bisecting ham sandwiches"
    - "ppp completeness with connections to cryptography"
    - "unique end of potential line"
    - "consensus halving is ppa complete"
    - "integer factoring and modular square roots"
    - "on the complexity of finding falsifying assignments for herbrand disjunctions"
    - "the complexity of non monotone markets"
    - "settling the complexity of arrow debreu equilibria in markets with additively separable utilities"

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.CC(Computational Complexity)