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: "approximation and hardness for token swapping"
  Abstract: Given a graph $G=(V,E)$ with $V=\{1,\ldots,n\}$, we place on every vertex a token $T_1,\ldots,T_n$. A swap is an exchange of tokens on adjacent vertices. We consider the algorithmic question of finding a shortest sequence of swaps such that token $T_i$ is on vertex $i$. We are able to achieve essentially matching upper and lower bounds, for exact algorithms and approximation algorithms. For exact algorithms, we rule out any $2^{o(n)}$ algorithm under the ETH. This is matched with a simple $2^{O(n\log n)}$ algorithm based on a breadth-first search in an auxiliary graph. We show one general $4$-approximation and show APX-hardness. Thus, there is a small constant $\delta>1$ such that every polynomial time approximation algorithm has approximation factor at least $\delta$. Our results also hold for a generalized version, where tokens and vertices are colored. In this generalized version each token must go to a vertex with the same color.

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"
    - "the time complexity of the token swapping problem and its parallel variants"
    - "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 "reconfiguration of connected graph partitions"):
  with members:
    - "fair redistricting is hard"
    - "token sliding on chordal graphs"
    - "linear time algorithm for sliding tokens on trees"
    - "distributed evolutionary graph partitioning"

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

Connected through hyperedge HE-4 (induced by source paper "new results on routing via matchings on graphs"):
  with members:
    - "the time complexity of the token swapping problem and its parallel variants"
    - "routing and sorting via matchings on graphs"
    - "acquaintance time of a graph"

Connected through hyperedge HE-5 (induced by source paper "complexity of token swapping and its variants"):
  with members:
    - "swapping colored tokens on graphs"
    - "complexity of finding perfect bipartite matchings minimizing the number of intersecting edges"
    - "subexponential time algorithms for finding small tree and path decompositions"
    - "optimal parameterized algorithms for planar facility location problems using voronoi diagrams"
    - "linear time algorithm for sliding tokens on trees"
    - "deciding first order properties of nowhere dense graphs"
    - "sorting of permutations by cost constrained transpositions"

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)