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: "combinatorial optimization with 2 joins"
  Abstract: A 2-join is an edge cutset that naturally appears in decomposition of several classes of graphs closed under taking induced subgraphs, such as perfect graphs and claw-free graphs. In this paper we construct combinatorial polynomial time algorithms for finding a maximum weighted clique, a maximum weighted stable set and an optimal coloring for a class of perfect graphs decomposable by 2-joins: the class of perfect graphs that do not have a balanced skew partition, a 2-join in the complement, nor a homogeneous pair. The techniques we develop are general enough to be easily applied to finding a maximum weighted stable set for another class of graphs known to be decomposable by 2-joins, namely the class of even-hole-free graphs that do not have a star cutset. We also give a simple class of graphs decomposable by 2-joins into bipartite graphs and line graphs, and for which finding a maximum stable set is NP-hard. This shows that having holes all of the same parity gives essential properties for the use of 2-joins in computing stable sets.

Connected through hyperedge HE-1 (induced by source paper "three in a tree in near linear time"):
  with members:
    - "graph pattern detection hardness for all induced patterns and faster non induced cycles"
    - "a faster algorithm to recognize even hole free graphs"
    - "on the structure of pan even hole free graphs"
    - "powers of tensors and fast matrix multiplication"
    - "detecting an induced net subdivision"
    - "large induced subgraphs via triangulations and cmso"
    - "induced disjoint paths in claw free graphs"
    - "detecting 2 joins faster"

Connected through hyperedge HE-2 (induced by source paper "a polynomial turing kernel for weighted independent set in bull free graphs"):
  with members:
    - "turing kernelization for finding long paths and cycles in restricted graph classes"
    - "improved fpt algorithms for weighted independent set in bull free graphs"
    - "coloring perfect graphs with no balanced skew partitions"
    - "maximum weight independent sets in odd hole free graphs without dart or without bull"
    - "on finding directed trees with many leaves"
    - "kernel s for problems with no kernel on out trees with many leaves"

Connected through hyperedge HE-3 (induced by source paper "a faster algorithm to recognize even hole free graphs"):
  with members:
    - "detecting 2 joins faster"
    - "algorithms for perfectly contractile graphs"

Connected through hyperedge HE-4 (induced by source paper "coloring perfect graphs with no balanced skew partitions"):
  with members:
    - "detecting 2 joins faster"

Connected through hyperedge HE-5 (induced by source paper "detecting 2 joins faster"):
  with members:
    - "linear time split decomposition revisited"

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)