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 time complexity of the token swapping problem and its parallel variants"
  Abstract: The token swapping problem (TSP) and its colored version are reconfiguration problems on graphs. This paper is concerned with the complexity of the TSP and two new variants; namely parallel TSP and parallel colored TSP. For a given graph where each vertex has a unique token on it, the TSP requires to find a shortest way to modify a token placement into another by swapping tokens on adjacent vertices. In the colored version, vertices and tokens are colored and the goal is to relocate tokens so that each vertex has a token of the same color. Their parallel versions allow simultaneous swaps on non-incident edges in one step. We investigate the time complexity of several restricted cases of those problems and show when those problems become tractable and remain intractable.

Connected through hyperedge HE-1 (induced by source paper "token swapping on trees"):
  with members:
    - "swapping colored tokens on graphs"
    - "the time complexity of permutation routing via matching token swapping and a variant"
    - "approximation and hardness for token swapping"
    - "pebble games proof complexity and time space trade offs"
    - "the complexity of change"
    - "an efficient algorithm for the diameter of cayley graphs generated by transposition trees"
    - "pancake flipping is hard"
    - "playing games with algorithms algorithmic combinatorial game theory"

Connected through hyperedge HE-2 (induced by source paper "finding optimal solutions to token swapping by conflict based search and reduction to sat"):
  with members:
    - "optimal target assignment and path finding for teams of agents"
    - "complexity of token swapping and its variants"
    - "optimal multi robot path planning on graphs structure and computational complexity"
    - "planning optimal paths for multiple robots on graphs"
    - "exploiting subgraph structure in multi robot path planning"

Connected through hyperedge HE-3 (induced by source paper "swapping colored tokens on graphs"):
  with members:
    - "approximation and hardness for token swapping"
    - "complexity of token swapping and its variants"
    - "the complexity of change"

Connected through hyperedge HE-4 (induced by source paper "lazy modeling of variants of token swapping problem and multi agent path finding through combination of satisfiability modulo theories and conflict based search"):
  with members:
    - "optimal multi robot path planning on graphs structure and computational complexity"
    - "planning optimal paths for multiple robots on graphs"
    - "exploiting subgraph structure in multi robot path planning"

Connected through hyperedge HE-5 (induced by source paper "new results on routing via matchings on graphs"):
  with members:
    - "approximation and hardness for token swapping"
    - "routing and sorting via matchings on graphs"
    - "acquaintance time of a graph"

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)