human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "the k in a tree problem for graphs of girth at least k"):
  Abstract: For all integers k>=3, we give an O(n^4)-time algorithm for the problem whose instance is a graph G of girth at least k together with k vertices and whose question is ''Does G contains an induced subgraph containing the k vertices and isomorphic to a tree?''. This directly follows for k=3 from the three-in-a-tree algorithm of Chudnovsky and Seymour and for k=4 from a result of Derhy, Picouleau and Trotignon. Here we solve the problem for k>=5. Our algorithm relies on a structural description of graphs of girth at least k that do not contain an induced tree covering k given vertices (k>=5).

Includes members:
  Member "detecting induced subgraphs":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "three in a tree in near linear time")
  Member "the four in a tree problem in triangle free graphs":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "three in a tree in near linear time")

Question: Please tell me which class the source paper 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)