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: "a note on minimal matching covered graphs"
  Abstract: A graph is called matching covered if for its every edge there is a maximum matching containing it. It is shown that minimal matching covered graphs without isolated vertices contain a perfect matching.

Connected through hyperedge HE-1 (induced by source paper "on disjoint matchings in cubic graphs maximum 2 edge colorable and maximum 3 edge colorable subgraphs"):
  with members:
    - "on disjoint matchings in cubic graphs"
    - "characterization of a class of graphs related to pairs of disjoint matchings"
    - "note on edge disjoint pairs of matchings"
    - "on trees with a maximum proper partial 0 1 coloring containing a maximum matching"

Connected through hyperedge HE-2 (induced by source paper "on disjoint matchings in cubic graphs"):
  with members:
    - "characterization of a class of graphs related to pairs of disjoint matchings"
    - "note on edge disjoint pairs of matchings"
    - "on trees with a maximum proper partial 0 1 coloring containing a maximum matching"

Connected through hyperedge HE-3 (induced by source paper "characterization of a class of graphs related to pairs of disjoint matchings"):
  with members:
    - "on complexity of special maximum matchings constructing"
    - "note on edge disjoint pairs of matchings"
    - "two polynomial algorithms for special maximum matching constructing in trees"
    - "on trees with a maximum proper partial 0 1 coloring containing a maximum matching"

Connected through hyperedge HE-4 (induced by source paper "note on edge disjoint pairs of matchings"):
  with members:
    - "characterization of a class of graphs related to pairs of disjoint matchings"
    - "on trees with a maximum proper partial 0 1 coloring containing a maximum matching"

Connected through hyperedge HE-5 (induced by source paper "on a constructive characterization of a class of trees related to pairs of disjoint matchings"):
  with members:
    - "characterization of a class of graphs related to pairs of disjoint matchings"
    - "on complexity of special maximum matchings constructing"
    - "note on edge disjoint pairs of matchings"
    - "two polynomial algorithms for special maximum matching constructing in trees"
    - "on trees with a maximum proper partial 0 1 coloring containing a maximum matching"

Connected through hyperedge HE-6 (induced by source paper "the complexity of determining existence a hamiltonian cycle is o n 3"):
  with members:
    - "the complexity of hcp in digraps with degree bound two"

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)