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: "reassembling trees for the traveling salesman"
  Abstract: Many recent approximation algorithms for different variants of the traveling salesman problem (asymmetric TSP, graph TSP, s-t-path TSP) exploit the well-known fact that a solution of the natural linear programming relaxation can be written as convex combination of spanning trees. The main argument then is that randomly sampling a tree from such a distribution and then completing the tree to a tour at minimum cost yields a better approximation guarantee than simply taking a minimum cost spanning tree (as in Christofides' algorithm). We argue that an additional step can help: reassembling the spanning trees before sampling. Exchanging two edges in a pair of spanning trees can improve their properties under certain conditions. We demonstrate the usefulness for the metric s-t-path TSP by devising a deterministic polynomial-time algorithm that improves on Seb\H{o}'s previously best approximation ratio of 8/5.

Connected through hyperedge HE-1 (induced by source paper "reducing path tsp to tsp"):
  with members:
    - "beating the integrality ratio for s t tours in graphs"
    - "a 1 5 approximation for path tsp"
    - "better s t tours by gao trees"
    - "eight fifth approximation for the path tsp"
    - "new inapproximability bounds for tsp"
    - "approximating minimum cost connected t joins"
    - "improving christofides algorithm for the s t path tsp"
    - "13 9 approximation for graphic tsp"

Connected through hyperedge HE-2 (induced by source paper "an improved upper bound on the integrality ratio for the s t path tsp"):
  with members:
    - "a 1 5 approximation for path tsp"
    - "layers and matroids for the traveling salesman s paths"
    - "better s t tours by gao trees"
    - "eight fifth approximation for the path tsp"
    - "improving christofides algorithm for the s t path tsp"

Connected through hyperedge HE-3 (induced by source paper "a 1 5 approximation for path tsp"):
  with members:
    - "better s t tours by gao trees"
    - "on the metric s t path traveling salesman problem"
    - "13 9 approximation for graphic tsp"
    - "minimum cuts in near linear time"

Connected through hyperedge HE-4 (induced by source paper "approaching frac 3 2 for the s t path tsp"):
  with members:
    - "a 1 5 approximation for path tsp"
    - "an improved upper bound on the integrality ratio for the s t path tsp"
    - "layers and matroids for the traveling salesman s paths"
    - "better s t tours by gao trees"
    - "improving christofides algorithm for the s t path tsp"

Connected through hyperedge HE-5 (induced by source paper "the salesman s improved paths 3 2 1 34 integrality gap and approximation ratio"):
  with members:
    - "better s t tours by gao trees"
    - "on the metric s t path traveling salesman problem"
    - "approximating minimum cost connected t joins"

Connected through hyperedge HE-6 (induced by source paper "an experimental evaluation of the best of many christofides algorithm for the traveling salesman problem"):
  with members:
    - "better s t tours by gao trees"
    - "on the metric s t path traveling salesman problem"
    - "eight fifth approximation for the path tsp"
    - "improving christofides algorithm for the s t path tsp"
    - "approximating graphic tsp by matchings"
    - "13 9 approximation for graphic tsp"

Connected through hyperedge HE-7 (induced by source paper "better s t tours by gao trees"):
  with members:
    - "layers and matroids for the traveling salesman s paths"
    - "an experimental evaluation of the best of many christofides algorithm for the traveling salesman problem"
    - "on the metric s t path traveling salesman problem"
    - "eight fifth approximation for the path tsp"
    - "approximating minimum cost connected t joins"
    - "improving christofides algorithm for the s t path tsp"

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)