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 classes ppa k existence from arguments modulo k"
  Abstract: The complexity classes PPA-$k$, $k \geq 2$, have recently emerged as the main candidates for capturing the complexity of important problems in fair division, in particular Alon's Necklace-Splitting problem with $k$ thieves. Indeed, the problem with two thieves has been shown complete for PPA = PPA-2. In this work, we present structural results which provide a solid foundation for the further study of these classes. Namely, we investigate the classes PPA-$k$ in terms of (i) equivalent definitions, (ii) inner structure, (iii) relationship to each other and to other TFNP classes, and (iv) closure under Turing reductions.

Connected through hyperedge HE-1 (induced by source paper "consenus halving does it ever get easier"):
  with members:
    - "the hairy ball problem is ppad complete"
    - "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 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 "on the complexity of modulo q arguments and the chevalley warning theorem"):
  with members:
    - "the complexity of splitting necklaces and bisecting ham sandwiches"
    - "ppp completeness with connections to cryptography"
    - "on the polynomial parity argument complexity of the combinatorial nullstellensatz"
    - "consensus halving is ppa complete"
    - "integer factoring and modular square roots"
    - "settling the complexity of computing approximate two player nash equilibria"

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)