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 relating edges in graphs without cycles of length 4"
  Abstract: An edge xy is relating in the graph G if there is an independent set S, containing neither x nor y, such that S_{x} and S_{y} are both maximal independent sets in G. It is an NP-complete problem to decide whether an edge is relating (Brown, Nowakowski, Zverovich, 2007). We show that the problem remains NP-complete even for graphs without cycles of length 4 and 5. On the other hand, for graphs without cycles of length 4 and 6, the problem can be solved in polynomial time.

Connected through hyperedge HE-1 (induced by source paper "recognizing generating subgraphs in graphs without cycles of lengths 6 and 7"):
  with members:
    - "complexity results for generating subgraphs"
    - "well covered graphs without cycles of lengths 4 5 and 6"

Connected through hyperedge HE-2 (induced by source paper "complexity results on w well covered graphs"):
  with members:
    - "weighted well covered claw free graphs"
    - "weighted well covered graphs without cycles of length 4 6 and 7"

Connected through hyperedge HE-3 (induced by source paper "complexity results for generating subgraphs"):
  with members:
    - "weighted well covered claw free graphs"
    - "well covered graphs without cycles of lengths 4 5 and 6"

Connected through hyperedge HE-4 (induced by source paper "weighted well covered claw free graphs"):
  with members:
    - "well covered graphs without cycles of lengths 4 5 and 6"
    - "weighted well covered graphs without cycles of length 4 6 and 7"

Connected through hyperedge HE-5 (induced by source paper "well covered graphs without cycles of lengths 4 5 and 6"):
  with members:
    - "complexity results on w well covered graphs"
    - "weighted well covered claw free 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)