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: "clique width and edge contraction"
  Abstract: We prove that edge contractions do not preserve the property that a set of graphs has bounded clique-width. This property is preserved by contractions of edges, one end of which is a vertex of degree 2.

Connected through hyperedge HE-1 (induced by source paper "the behavior of clique width under graph operations and graph transformations"):
  with members:
    - "a sat approach to clique width"
    - "seidel minor permutation graphs and combinatorial properties"
    - "nlc 2 graph recognition and isomorphism"

Connected through hyperedge HE-2 (induced by source paper "induced minor free graphs isomorphism and clique width"):
  with members:
    - "graph isomorphism in quasipolynomial time"
    - "isomorphism testing for graphs of bounded rank width"
    - "clique width of graph classes defined by two forbidden induced subgraphs"
    - "reduction techniques for graph isomorphism in the context of width parameters"
    - "classifying the clique width of h free bipartite graphs"
    - "towards an isomorphism dichotomy for hereditary graph classes"
    - "fixed parameter tractable canonization and isomorphism test for graphs of bounded treewidth"
    - "graph isomorphism for graph classes characterized by two forbidden induced subgraphs"

Connected through hyperedge HE-3 (induced by source paper "clique width of graph classes defined by two forbidden induced subgraphs"):
  with members:
    - "the behavior of clique width under graph operations and graph transformations"
    - "bounding the clique width of h free chordal graphs"
    - "isomorphism testing for graphs of bounded rank width"
    - "bounding the clique width of h free split graphs"
    - "bounding clique width via perfect graphs"
    - "classifying the clique width of h free bipartite graphs"
    - "a survey on the computational complexity of colouring graphs with forbidden subgraphs"
    - "improved bounds for the flat wall theorem"

Connected through hyperedge HE-4 (induced by source paper "bounding clique width via perfect graphs"):
  with members:
    - "the behavior of clique width under graph operations and graph transformations"
    - "bounding the clique width of h free chordal graphs"
    - "isomorphism testing for graphs of bounded rank width"
    - "bounding the clique width of h free split graphs"
    - "clique width of graph classes defined by two forbidden induced subgraphs"
    - "classifying the clique width of h free bipartite graphs"
    - "towards an isomorphism dichotomy for hereditary graph classes"
    - "a sat approach to clique width"

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)