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: "on symbolic ultrametrics cotree representations and cograph edge decompositions and partitions"
  Abstract: Symbolic ultrametrics define edge-colored complete graphs K_n and yield a simple tree representation of K_n. We discuss, under which conditions this idea can be generalized to find a symbolic ultrametric that, in addition, distinguishes between edges and non-edges of arbitrary graphs G=(V,E) and thus, yielding a simple tree representation of G. We prove that such a symbolic ultrametric can only be defined for G if and only if G is a so-called cograph. A cograph is uniquely determined by a so-called cotree. As not all graphs are cographs, we ask, furthermore, what is the minimum number of cotrees needed to represent the topology of G. The latter problem is equivalent to find an optimal cograph edge k-decomposition {E_1,...,E_k} of E so that each subgraph (V,E_i) of G is a cograph. An upper bound for the integer k is derived and it is shown that determining whether a graph has a cograph 2-decomposition, resp., 2-partition is NP-complete.

Connected through hyperedge HE-1 (induced by source paper "cograph editing merging modules is equivalent to editing p4 s"):
  with members:
    - "exact and heuristic algorithms for cograph editing"
    - "reconstructing gene trees from fitch s xenology relation"
    - "partial homology relations satisfiability in terms of di cographs"
    - "the mathematics of xenology di cographs symbolic ultrametrics 2 structures and tree representable systems of binary relations"
    - "phylogenomics with paralogs"
    - "on tree representations of relations and graphs symbolic ultrametrics and cograph edge decompositions"
    - "parameterized algorithms for modular width"
    - "on the non existence of polynomial kernels for p l free edge modification problems"

Connected through hyperedge HE-2 (induced by source paper "forbidden time travel characterization of time consistent tree reconciliation maps"):
  with members:
    - "from event labeled gene trees to species trees"
    - "from event labeled gene trees with horizontal gene transfer to species trees"
    - "the mathematics of xenology di cographs symbolic ultrametrics 2 structures and tree representable systems of binary relations"
    - "phylogenomics with paralogs"
    - "on tree representations of relations and graphs symbolic ultrametrics and cograph edge decompositions"

Connected through hyperedge HE-3 (induced by source paper "the mathematics of xenology di cographs symbolic ultrametrics 2 structures and tree representable systems of binary relations"):
  with members:
    - "from event labeled gene trees to species trees"
    - "techniques for the cograph editing problem module merge is equivalent to editing p4s"
    - "phylogenomics with paralogs"
    - "on tree representations of relations and graphs symbolic ultrametrics and cograph edge decompositions"

Connected through hyperedge HE-4 (induced by source paper "inference of phylogenetic trees from the knowledge of rare evolutionary events"):
  with members:
    - "the mathematics of xenology di cographs symbolic ultrametrics 2 structures and tree representable systems of binary relations"
    - "phylogenomics with paralogs"
    - "on tree representations of relations and graphs symbolic ultrametrics and cograph edge decompositions"

Connected through hyperedge HE-5 (induced by source paper "beyond representing orthology relations by trees"):
  with members:
    - "reconstructing phylogenetic level 1 networks from nondense binet and trinet sets"

Connected through hyperedge HE-6 (induced by source paper "on tree representations of relations and graphs symbolic ultrametrics and cograph edge decompositions"):
  with members:
    - "from event labeled gene trees to species trees"
    - "phylogenomics with paralogs"
    - "partial star products a local covering approach for the recognition of approximate cartesian product 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)