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: "recognizing simple triangle graphs by restricted 2 chain subgraph cover"
  Abstract: A simple-triangle graph (also known as a PI graph) is the intersection graph of a family of triangles defined by a point on a horizontal line and an interval on another horizontal line. The recognition problem for simple-triangle graphs was a longstanding open problem, and recently a polynomial-time algorithm has been given (SIAM J. Discrete Math. 29(3):1150–1185, 2015). Along with the approach of this paper, we show a simpler recognition algorithm for simple-triangle graphs. To do this, we provide a polynomial-time algorithm to solve the following problem: Given a bipartite graph G and a set F of edges of G, find a 2-chain subgraph cover of G such that one of two chain subgraphs has no edges in F.

Connected through hyperedge HE-1 (induced by source paper "linear semiorders and their incomparability graphs"):
  with members:
    - "a vertex ordering characterization of simple triangle graphs"
    - "the recognition of simple triangle graphs and of linear interval orders is polynomial"

Connected through hyperedge HE-2 (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"
    - "a recognition algorithm for simple triangle graphs"
    - "fully polynomial time parameterized computations for graphs and matrices of low treewidth"
    - "graph isomorphism completeness for trapezoid graphs"
    - "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-3 (induced by source paper "a recognition algorithm for simple triangle graphs"):
  with members:
    - "a vertex ordering characterization of simple triangle graphs"
    - "graph isomorphism completeness for trapezoid 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 "a vertex ordering characterization of simple triangle graphs"):
  with members:
    - "graph isomorphism completeness for trapezoid graphs"
    - "ordering without forbidden patterns"
    - "the recognition of simple triangle graphs and of linear interval orders is polynomial"

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)