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: "unique perfect phylogeny characterizations via uniquely representable chordal graphs"
  Abstract: The perfect phylogeny problem is a classic problem in computational biology, where#N#         we seek an unrooted phylogeny that is compatible with a set of qualitative characters. Such#N#         a tree exists precisely when an intersection graph associated with the character set,#N#         called the partition intersection graph, can be triangulated using a restricted set of fill#N#         edges. Semple and Steel used the partition intersection graph to characterize when a#N#         character set has a unique perfect phylogeny. Bordewich, Huber, and Semple showed how to#N#         use the partition intersection graph to find a maximum compatible set of characters. In#N#         this paper, we build on these results, characterizing when a unique perfect phylogeny#N#         exists for a subset of partial characters. Our characterization is stated in terms of#N#         minimal triangulations of the partition intersection graph that are uniquely representable,#N#         also known as ur-chordal graphs. Our characterization is motivated by the structure of#N#         ur-chordal graphs, and the fact that the block structure of minimal triangulations is#N#         mirrored in the graph that has been triangulated.

Connected through hyperedge HE-1 (induced by source paper "approximately counting locally optimal structures"):
  with members:
    - "the complexity of approximately counting tree homomorphisms"
    - "approximating the partition function of the ferromagnetic potts model"
    - "finding induced subgraphs via minimal triangulations"
    - "treewidth computation and extremal combinatorics"

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)