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: "eight fifth approximation for the path tsp"
  Abstract: We prove the approximation ratio 8/5 for the metric {s,t}-path-TSP, and more generally for shortest connected T-joins.#R##N##R##N#The algorithm that achieves this ratio is the simple "Best of Many" version of Christofides' algorithm (1976), suggested by An, Kleinberg and Shmoys (2012), which consists in determining the best Christofides {s,t}-tour out of those constructed from a family $\mathcal{F}_+$ of trees having a convex combination dominated by an optimal solution x* of the Held-Karp relaxation. They give the approximation guarantee $\frac{\sqrt{5}+1}{2}$ for such an {s,t}-tour, which is the first improvement after the 5/3 guarantee of Hoogeveen's Christofides type algorithm (1991). Cheriyan, Friggstad and Gao (2012) extended this result to a 13/8-approximation of shortest connected T-joins, for |T|≥4.#R##N##R##N#The ratio 8/5 is proved by simplifying and improving the approach of An, Kleinberg and Shmoys that consists in completing x*/2 in order to dominate the cost of "parity correction" for spanning trees. We partition the edge-set of each spanning tree in $\mathcal{F}_+$ into an {s,t}-path (or more generally, into a T-join) and its complement, which induces a decomposition of x*. This decomposition can be refined and then efficiently used to complete x*/2 without using linear programming or particular properties of T, but by adding to each cut deficient for x*/2 an individually tailored explicitly given vector, inherent in x*.#R##N##R##N#A simple example shows that the Best of Many Christofides algorithm may not find a shorter {s,t}-tour than 3/2 times the incidentally common optima of the problem and of its fractional relaxation.

Connected through hyperedge HE-1 (induced by source paper "constant factor approximation algorithms for parity constrained facility location problems"):
  with members:
    - "a tree structure for dynamic facility location"
    - "on facility location with general lower bounds"
    - "online facility location with deletions"
    - "optimal parameterized algorithms for planar facility location problems using voronoi diagrams"
    - "facility location in evolving metrics"
    - "lp based algorithms for capacitated facility location"
    - "local search based approximation algorithms for mobile facility location problems"
    - "fast clustering with lower bounds no customer too far no shop too small"

Connected through hyperedge HE-2 (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"
    - "reassembling trees for the traveling salesman"
    - "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-3 (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"
    - "reassembling trees for the traveling salesman"
    - "improving christofides algorithm for the s t path tsp"

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"
    - "on the metric s t path traveling salesman problem"
    - "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"
    - "on the metric s t path traveling salesman problem"
    - "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"
    - "on the metric s t path traveling salesman problem"
    - "approximating minimum cost connected t joins"
    - "improving christofides algorithm for the s t path tsp"

Connected through hyperedge HE-7 (induced by source paper "graph tsp from steiner cycles"):
  with members:
    - "shorter tours by nicer ears 7 5 approximation for graphic tsp 3 2 for the path version and 4 3 for two edge connected subgraphs"
    - "approximating graphic tsp by matchings"
    - "a 4 3 approximation for tsp on cubic 3 edge connected graphs"
    - "13 9 approximation for graphic tsp"

Connected through hyperedge HE-8 (induced by source paper "tsp tours in cubic graphs beyond 4 3"):
  with members:
    - "approximation hardness of graphic tsp on cubic graphs"
    - "a 9 7 approximation algorithm for graphic tsp in cubic bipartite graphs"
    - "improved inapproximability for tsp"
    - "on the integrality gap of the subtour lp for the 1 2 tsp"
    - "improving christofides algorithm for the s t path tsp"
    - "approximating graphic tsp by matchings"
    - "a 4 3 approximation for tsp on cubic 3 edge connected graphs"
    - "a proof of the boyd carr conjecture"

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)