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 tree representations of relations and graphs symbolic ultrametrics and cograph edge decompositions"
  Abstract: Tree representations of (sets of) symmetric binary relations, or equivalently edge-colored undirected graphs, are of central interest, e.g.\ in phylogenomics. In this context symbolic ultrametrics play a crucial role. Symbolic ultrametrics define an edge-colored complete graph that allows to represent the topology of this graph as a vertex-colored tree. Here, we are interested in the structure and the complexity of certain combinatorial problems resulting from considerations based on symbolic ultrametrics, and on algorithms to solve them. #R##N#This includes, the characterization of symbolic ultrametrics that additionally distinguishes between edges and non-edges of \emph{arbitrary} edge-colored graphs $G$ and thus, yielding a tree representation of $G$, by means of so-called cographs. Moreover, we address the problem of finding "closest" symbolic ultrametrics and show the NP-completeness of the three problems: symbolic ultrametric editing, completion and deletion. Finally, as not all graphs are cographs, and hence, don't have a tree representation, we ask, furthermore, what is the minimum number of cotrees needed to represent the topology of an arbitrary non-cograph $G$. This is equivalent to find an optimal cograph edge $k$-decomposition $\{E_1,\dots,E_k\}$ of $E$ so that each subgraph $(V,E_i)$ of $G$ is a cograph. We investigate this problem in full detail, resulting in several new open problems, and NP-hardness results. #R##N#For all optimization problems proven to be NP-hard we will provide integer linear program (ILP) formulations to efficiently solve them.

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 symbolic ultrametrics cotree representations and cograph edge decompositions and partitions"
    - "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 symbolic ultrametrics cotree representations and cograph edge decompositions and partitions"

Connected through hyperedge HE-3 (induced by source paper "reconstructing gene trees from fitch s xenology relation"):
  with members:
    - "generalized fitch graphs edge labeled graphs that are explained by edge labeled trees"
    - "from event labeled gene trees to species trees"
    - "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"

Connected through hyperedge HE-4 (induced by source paper "from event labeled gene trees to species trees"):
  with members:
    - "the mathematics of xenology di cographs symbolic ultrametrics 2 structures and tree representable systems of binary relations"
    - "phylogenomics with paralogs"

Connected through hyperedge HE-5 (induced by source paper "partial homology relations satisfiability in terms of di cographs"):
  with members:
    - "the mathematics of xenology di cographs symbolic ultrametrics 2 structures and tree representable systems of binary relations"
    - "phylogenomics with paralogs"

Connected through hyperedge HE-6 (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 symbolic ultrametrics cotree representations and cograph edge decompositions and partitions"

Connected through hyperedge HE-7 (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 symbolic ultrametrics cotree representations and cograph edge decompositions and partitions"

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)