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 the core of a unicyclic graph"
  Abstract: A set S is independent in a graph G if no two vertices from S are adjacent. By core(G) we mean the intersection of all maximum independent sets. The independence number alpha(G) is the cardinality of a maximum independent set, while mu(G) is the size of a maximum matching in G. A connected graph having only one cycle, say C, is a unicyclic graph. In this paper we prove that if G is a unicyclic graph of order n and n-1 = alpha(G) + mu(G), then core(G) coincides with the union of cores of all trees in G-C.

Connected through hyperedge HE-1 (induced by source paper "on the critical difference of almost bipartite graphs"):
  with members:
    - "a set and collection lemma"
    - "vertices belonging to all critical independent sets of a graph"
    - "critical sets in bipartite graphs"
    - "a characterization of konig egervary graphs using a common property of all maximum matchings"

Connected through hyperedge HE-2 (induced by source paper "critical and maximum independent sets of a graph"):
  with members:
    - "on the power of simple reductions for the maximum independent set problem"
    - "a set and collection lemma"
    - "on the intersection of all critical sets of a unicyclic graph"
    - "vertices belonging to all critical independent sets of a graph"
    - "on the structure of the minimum critical independent set of a graph"
    - "critical sets in bipartite graphs"

Connected through hyperedge HE-3 (induced by source paper "monotonic properties of collections of maximum independent sets of a graph"):
  with members:
    - "a set and collection lemma"
    - "on the intersection of all critical sets of a unicyclic graph"
    - "vertices belonging to all critical independent sets of a graph"
    - "on the structure of the minimum critical independent set of a graph"
    - "critical sets in bipartite graphs"

Connected through hyperedge HE-4 (induced by source paper "computing unique maximum matchings in o m time for konig egervary graphs and unicyclic graphs"):
  with members:
    - "on the intersection of all critical sets of a unicyclic graph"
    - "very well covered graphs of girth at least four and local maximum stable set greedoids"

Connected through hyperedge HE-5 (induced by source paper "on the intersection of all critical sets of a unicyclic graph"):
  with members:
    - "a set and collection lemma"
    - "vertices belonging to all critical independent sets of a graph"
    - "on the structure of the minimum critical independent set of a graph"
    - "critical sets in bipartite 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)