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 the metric s t path traveling salesman problem"
  Abstract: We study the metric $s$-$t$ path Traveling Salesman Problem (TSP). [An, Kleinberg, and Shmoys, STOC 2012] improved on the long standing $\frac{5}{3}$-approximation factor and presented an algorithm that achieves an approximation factor of $\frac{1+\sqrt{5}}{2}\approx1.61803$. Later [Seb\H{o}, IPCO 2013] further improved the approximation factor to $\frac{8}{5}$. We present a simple, self-contained analysis that unifies both results; our main contribution is a \emph{unified correction vector}. We compare two different linear programming (LP) relaxations of the $s$-$t$ path TSP, namely, the path version of the Held-Karp LP relaxation for TSP and a weaker LP relaxation, and we show that both LPs have the same (fractional) optimal value. Also, we show that the minimum-cost of integral solutions of the two LPs are within a factor of $\frac{3}{2}$ of each other. We prove that a half-integral solution of the stronger LP-relaxation of cost $c$ can be rounded to an integral solution of cost at most $\frac{3}{2}c$. Additionally, we give a bad instance that presents obstructions to two obvious methods that aim for an approximation factor of $\frac{3}{2}$.

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

Connected through hyperedge HE-2 (induced by source paper "the unbounded integrality gap of a semidefinite relaxation of the traveling salesman problem"):
  with members:
    - "new inapproximability bounds for tsp"
    - "13 9 approximation for graphic tsp"

Connected through hyperedge HE-3 (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"
    - "reassembling trees for the traveling salesman"
    - "approximating minimum cost connected t joins"

Connected through hyperedge HE-4 (induced by source paper "reassembling trees for the traveling salesman"):
  with members:
    - "an experimental evaluation of the best of many christofides algorithm for the traveling salesman problem"
    - "better s t tours by gao trees"
    - "eight fifth approximation for the path tsp"
    - "approximating minimum cost connected t joins"
    - "improving christofides algorithm for the s t path tsp"
    - "approximating graphic tsp by matchings"
    - "13 9 approximation for graphic tsp"

Connected through hyperedge HE-5 (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"
    - "reassembling trees for the traveling salesman"
    - "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-6 (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"
    - "reassembling trees for the traveling salesman"
    - "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.DS(Data Structures and Algorithms)