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 "an improved upper bound on the integrality ratio for the s t path tsp"):
  Abstract: We give an improved analysis of the best-of-many Christofides algorithm with lonely edge deletion, which was proposed by Seb\H{o} and van Zuylen [2016]. This implies an improved upper bound on the integrality ratio of the standard LP relaxation for the $s$-$t$-path TSP.

Includes members:
  Member "a 1 5 approximation for path tsp":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "minimum scan cover with angular transition costs")
  Member "layers and matroids for the traveling salesman s paths":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "approaching frac 3 2 for the s t path tsp")
  Member "better s t tours by gao trees":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "reducing path tsp to tsp")
  Member "reassembling trees for the traveling salesman":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "reducing path tsp to tsp")
  Member "eight fifth approximation for the path tsp":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "constant factor approximation algorithms for parity constrained facility location problems")
  Member "improving christofides algorithm for the s t path tsp":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "reducing path tsp to tsp")

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)