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 matchings and limits to tractability"
  Abstract: We consider popular matching problems in both bipartite and non-bipartite graphs with strict preference lists. It is known that every stable matching is a min-size popular matching. A subclass of max-size popular matchings called dominant matchings has been well-studied in bipartite graphs: they always exist and there is a simple linear time algorithm to find one. #R##N#We show that stable and dominant matchings are the only two tractable subclasses of popular matchings in bipartite graphs; more precisely, we show that it is NP-complete to decide if $G$ admits a popular matching that is neither stable nor dominant. We also show a number of related hardness results, such as (tight) inapproximability of the maximum weight popular matching problem. In non-bipartite graphs, we show a strong negative result: it is NP-hard to decide whether a popular matching exists or not, and the same result holds if we replace popular with dominant. #R##N#On the positive side, we show the following results in any graph: - we identify a subclass of dominant matchings called strongly dominant matchings and show a linear time algorithm to decide if a strongly dominant matching exists or not; - we show an efficient algorithm to compute a popular matching of minimum cost in a graph with edge costs and bounded treewidth.

Connected through hyperedge HE-1 (induced by source paper "understanding popular matchings via stable matchings"):
  with members:
    - "max size popular matchings and extensions"
    - "popular matching in roommates setting is np hard"
    - "popular matchings with two sided preferences and one sided ties"
    - "popular edges and dominant matchings"

Connected through hyperedge HE-2 (induced by source paper "computational complexity of stable marriage and stable roommates and their variants"):
  with members:
    - "stable roommates with narcissistic single peaked and single crossing preferences"
    - "matchings under preferences strength of stability and trade offs"
    - "stable marriage with multi modal preferences"
    - "on treewidth and stable marriage"
    - "how hard is it to satisfy almost all roommates"
    - "balanced stable marriage how close is close enough"
    - "the stable roommates problem with short lists"
    - "acyclic preference systems in p2p networks"

Connected through hyperedge HE-3 (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 matching in roommates setting is np hard"
    - "extension complexity of independent set polytopes"
    - "popular edges and dominant matchings"
    - "the matching polytope has exponential extension complexity"

Connected through hyperedge HE-4 (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 matching in roommates setting is np hard"
    - "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-5 (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 matching in roommates setting is np hard"
    - "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-6 (induced by source paper "unpopularity factor in the marriage and roommates problems"):
  with members:
    - "popular matching in roommates setting is np hard"
    - "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-7 (induced by source paper "popularity stability and the dominant matching polytope"):
  with members:
    - "max size popular matchings and extensions"
    - "popular matching in roommates setting is np hard"
    - "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.DM(Discrete Mathematics)