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: "popular matching in roommates setting is np hard"
  Abstract: An input to the Popular Matching problem, in the roommates setting, consists of a graph $G$ and each vertex ranks its neighbors in strict order, known as its preference. In the Popular Matching problem the objective is to test whether there exists a matching $M^\star$ such that there is no matching $M$ where more people are happier with $M$ than with $M^\star$. In this paper we settle the computational complexity of the Popular Matching problem in the roommates setting by showing that the problem is NP-complete. Thus, we resolve an open question that has been repeatedly, explicitly asked over the last decade.

Connected through hyperedge HE-1 (induced by source paper "understanding popular matchings via stable matchings"):
  with members:
    - "max size popular matchings and extensions"
    - "popular matchings and limits to tractability"
    - "popular matchings with two sided preferences and one sided ties"
    - "popular edges and dominant matchings"

Connected through hyperedge HE-2 (induced by source paper "quasi popular matchings optimality and extended formulations"):
  with members:
    - "understanding popular matchings via stable matchings"
    - "unpopularity factor in the marriage and roommates problems"
    - "popular matchings and limits to tractability"
    - "extension complexity of independent set polytopes"
    - "popular edges and dominant matchings"
    - "the matching polytope has exponential extension complexity"

Connected through hyperedge HE-3 (induced by source paper "popular branchings and their dual certificates"):
  with members:
    - "the convergence of iterative delegations in liquid democracy in a social network"
    - "popular matchings and limits to tractability"
    - "the fluid mechanics of liquid democracy"
    - "binary voting with delegable proxy an analysis of liquid democracy"
    - "popular matchings with two sided preferences and one sided ties"
    - "popular edges and dominant matchings"

Connected through hyperedge HE-4 (induced by source paper "nc algorithms for popular matchings in one sided preference systems and related problems"):
  with members:
    - "parallel and distributed algorithms for the housing allocation problem"
    - "popular matchings and limits to tractability"
    - "planar graph perfect matching is in nc"
    - "bipartite perfect matching is in quasi nc"
    - "the complexity of the comparator circuit value problem"

Connected through hyperedge HE-5 (induced by source paper "unpopularity factor in the marriage and roommates problems"):
  with members:
    - "popular matchings and limits to tractability"
    - "popular matchings in complete graphs"
    - "random popular matchings with incomplete preference lists"
    - "scaling algorithms for weighted matching in general graphs"
    - "weighted popular matchings"

Connected through hyperedge HE-6 (induced by source paper "popularity stability and the dominant matching polytope"):
  with members:
    - "max size popular matchings and extensions"
    - "popular matchings and limits to tractability"
    - "popular matchings with two sided preferences and one sided ties"
    - "popular edges and dominant matchings"

Connected through hyperedge HE-7 (induced by source paper "popular matchings and limits to tractability"):
  with members:
    - "max size popular matchings and extensions"
    - "the popular roommates problem"
    - "popular edges and dominant matchings"

Connected through hyperedge HE-8 (induced by source paper "the popular roommates problem"):
  with members:
    - "max size popular matchings and extensions"
    - "popular matchings with two sided preferences and one sided ties"
    - "popular edges and dominant matchings"

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.DS(Data Structures and Algorithms)