human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "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.

Includes members:
  Member "a vertex ordering characterization of simple triangle graphs":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "linear semiorders and their incomparability graphs")
  Member "graph isomorphism completeness for trapezoid graphs":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "a linear time algorithm for maximum cardinality matching on cocomparability graphs")
  Member "the recognition of simple triangle graphs and of linear interval orders is polynomial":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "linear semiorders and their incomparability graphs")
  Member "extending partial representations of function graphs and permutation graphs":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "extending upward planar graph drawings")
  Member "the recognition of tolerance and bounded tolerance graphs":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "a linear time algorithm for maximum cardinality matching on cocomparability graphs")

Question: Please tell me which class the source paper 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)