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: "the coloring problem for classes with two small obstructions"
  Abstract: The coloring problem is studied in the paper for graph classes defined by two small forbidden induced subgraphs. We prove some sufficient conditions for effective solvability of the problem in such classes. As their corollary we determine the computational complexity for all sets of two connected forbidden induced subgraphs with at most five vertices except 13 explicitly enumerated cases

Connected through hyperedge HE-1 (induced by source paper "on colouring 2p_2 h free and p_5 h free graphs"):
  with members:
    - "solving the clique cover problem on bull c_4 free graphs"
    - "hereditary graph classes when the complexities of colouring and clique cover coincide"
    - "colouring diamond free graphs"
    - "complexity of coloring graphs without paths and cycles"

Connected through hyperedge HE-2 (induced by source paper "hereditary graph classes when the complexities of colouring and clique cover coincide"):
  with members:
    - "clique width for graph classes closed under complementation"
    - "solving the clique cover problem on bull c_4 free graphs"
    - "colouring diamond free graphs"
    - "classifying the clique width of h free bipartite graphs"
    - "complexity of coloring graphs without paths and cycles"

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

Connected through hyperedge HE-4 (induced by source paper "a complexity dichotomy for the dominating set problem"):
  with members:
    - "the coloring problem for p 5 p 5 free graphs and p 5 k p e free graphs is polynomial"

Connected through hyperedge HE-5 (induced by source paper "a survey on the computational complexity of colouring graphs with forbidden subgraphs"):
  with members:
    - "bounding the clique width of h free chordal graphs"
    - "three coloring graphs with no induced seven vertex path ii using a triangle"
    - "the coloring problem for p 5 p 5 free graphs and p 5 k p e free graphs is polynomial"
    - "bounding clique width via perfect graphs"
    - "clique width of graph classes defined by two forbidden induced subgraphs"
    - "narrowing the complexity gap for colouring c_s p_t free graphs"
    - "4 coloring p_6 free graphs with no induced 5 cycles"
    - "polynomial time algorithms for minimum weighted colorings of p_5 bar p _5 free graphs and related graph classes"

Connected through hyperedge HE-6 (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"

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)