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 approximation algorithm for atsp"):
  Abstract: We revisit the constant-factor approximation algorithm for the asymmetric traveling salesman problem by Svensson, Tarnawski, and Vegh. We improve on each part of this algorithm. We avoid the reduction to irreducible instances and thus obtain a simpler and much better reduction to vertebrate pairs. We also show that a slight variant of their algorithm for vertebrate pairs has a much smaller approximation ratio. Overall we improve the approximation ratio from $506$ to $22+\epsilon$ for any $\epsilon > 0$. This also improves the upper bound on the integrality ratio from $319$ to $22$.

Includes members:
  Member "the asymmetric traveling salesman path lp has constant integrality ratio":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "a constant factor approximation for directed latency in quasi polynomial time")
  Member "a constant factor approximation algorithm for the asymmetric traveling salesman problem":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "a constant factor approximation for directed latency in quasi polynomial time")
  Member "constant factor approximation for atsp with two edge weights":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "a constant factor approximation algorithm for the asymmetric traveling salesman problem")
  Member "approximating atsp by relaxing connectivity":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "the asymmetric traveling salesman path lp has constant integrality ratio")
  Member "effective resistance reducing flows spectrally thin trees and asymmetric tsp":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "a spectral approach to network design")

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)