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: "graph isomorphism completeness for trapezoid graphs"
  Abstract: The complexity of the graph isomorphism problem for trapezoid graphs has been open over a decade. This paper shows that the problem is GI-complete. More precisely, we show that the graph isomorphism problem is GI-complete for comparability graphs of partially ordered sets with interval dimension 2 and height 3. In contrast, the problem is known to be solvable in polynomial time for comparability graphs of partially ordered sets with interval dimension at most 2 and height at most 2.

Connected through hyperedge HE-1 (induced by source paper "a linear time algorithm for maximum cardinality matching on cocomparability graphs"):
  with members:
    - "parameterized aspects of triangle enumeration"
    - "when can graph hyperbolicity be computed in linear time"
    - "recognizing simple triangle graphs by restricted 2 chain subgraph cover"
    - "a recognition algorithm for simple triangle graphs"
    - "fully polynomial time parameterized computations for graphs and matrices of low treewidth"
    - "polynomial fixed parameter algorithms a case study for longest path on interval graphs"
    - "new geometric representations and domination problems on tolerance and multitolerance graphs"
    - "linear time lexdfs on cocomparability graphs"

Connected through hyperedge HE-2 (induced by source paper "recognizing simple triangle graphs by restricted 2 chain subgraph cover"):
  with members:
    - "a vertex ordering characterization of simple triangle graphs"
    - "the recognition of simple triangle graphs and of linear interval orders is polynomial"
    - "extending partial representations of function graphs and permutation graphs"
    - "the recognition of tolerance and bounded tolerance graphs"

Connected through hyperedge HE-3 (induced by source paper "a recognition algorithm for simple triangle graphs"):
  with members:
    - "recognizing simple triangle graphs by restricted 2 chain subgraph cover"
    - "a vertex ordering characterization of simple triangle graphs"
    - "the recognition of simple triangle graphs and of linear interval orders is polynomial"
    - "the recognition of tolerance and bounded tolerance graphs"

Connected through hyperedge HE-4 (induced by source paper "graph isomorphism restricted by lists"):
  with members:
    - "algorithmic aspects of regular graph covers"
    - "induced minor free graphs isomorphism and clique width"
    - "polynomial time algorithm for isomorphism of graphs with clique width at most three"
    - "canonizing graphs of bounded tree width in logspace"
    - "graph isomorphism in quasipolynomial time"
    - "graph isomorphism for bounded genus graphs in linear time"
    - "iv matching is strongly np hard"
    - "isomorphism testing for graphs of bounded rank width"

Connected through hyperedge HE-5 (induced by source paper "a vertex ordering characterization of simple triangle graphs"):
  with members:
    - "recognizing simple triangle graphs by restricted 2 chain subgraph cover"
    - "ordering without forbidden patterns"
    - "the recognition of simple triangle graphs and of linear interval orders is polynomial"

Connected through hyperedge HE-6 (induced by source paper "a simpler recognition algorithm for simple triangle graphs"):
  with members:
    - "the recognition of simple triangle graphs and of linear interval orders is polynomial"
    - "the recognition of tolerance and bounded tolerance graphs"

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)