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: "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"
  Abstract: We prove new results for approximating the graphic TSP and some related problems. We obtain polynomial-time algorithms with improved approximation guarantees. #R##N#For the graphic TSP itself, we improve the approximation ratio to 7/5. For a generalization, the connected-$T$-join problem, we obtain the first nontrivial approximation algorithm, with ratio 3/2. This contains the graphic $s$-$t$-path-TSP as a special case. Our improved approximation guarantee for finding a smallest 2-edge-connected spanning subgraph is 4/3. #R##N#The key new ingredient of all our algorithms is a special kind of ear-decomposition optimized using forest representations of hypergraphs. The same methods also provide the lower bounds (arising from LP relaxations) that we use to deduce the approximation ratios.

Connected through hyperedge HE-1 (induced by source paper "travelling on graphs with small highway dimension"):
  with members:
    - "hierarchy of transportation network parameters and hardness results"
    - "the parameterized hardness of the k center problem in transportation networks"
    - "a 1 varepsilon embedding of low highway dimension graphs into bounded treewidth graphs"
    - "structural parameters tight bounds and approximation for k r center"
    - "beyond highway dimension small distance labels using tree skeletons"
    - "solving generalized maximum weight connected subgraph problem for network enrichment analysis"
    - "fixed parameter approximations for k center problems in low highway dimension graphs"
    - "the traveling salesman problem low dimensionality implies a polynomial time approximation scheme"

Connected through hyperedge HE-2 (induced by source paper "efficient constructions of convex combinations for 2 edge connected subgraphs on fundamental classes"):
  with members:
    - "coloring down 3 2 approximation for special cases of the weighted tree augmentation problem"
    - "shorter tours and longer detours uniform covers and a bit beyond"
    - "a proof of the boyd carr conjecture"

Connected through hyperedge HE-3 (induced by source paper "a constant factor approximation algorithm for the asymmetric traveling salesman problem"):
  with members:
    - "the asymmetric traveling salesman path lp has constant integrality ratio"
    - "constant factor approximation for atsp with two edge weights"
    - "approximating atsp by relaxing connectivity"
    - "effective resistance reducing flows spectrally thin trees and asymmetric tsp"
    - "new inapproximability bounds for tsp"
    - "improving christofides algorithm for the s t path tsp"
    - "13 9 approximation for graphic tsp"
    - "the asymmetric traveling salesman problem on graphs with bounded genus"

Connected through hyperedge HE-4 (induced by source paper "shorter tours and longer detours uniform covers and a bit beyond"):
  with members:
    - "coloring down 3 2 approximation for special cases of the weighted tree augmentation problem"
    - "the traveling salesman problem on cubic and subcubic graphs"
    - "13 9 approximation for graphic tsp"

Connected through hyperedge HE-5 (induced by source paper "graph tsp from steiner cycles"):
  with members:
    - "eight fifth approximation for the path tsp"
    - "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-6 (induced by source paper "an improved analysis of the m omke svensson algorithm for graph tsp on subquartic graphs"):
  with members:
    - "improving christofides algorithm for the s t path tsp"
    - "approximating graphic tsp by matchings"
    - "the traveling salesman problem on cubic and subcubic graphs"
    - "13 9 approximation for graphic tsp"

Connected through hyperedge HE-7 (induced by source paper "distributed multi depot routing without communications"):
  with members:
    - "approximating graphic tsp by matchings"
    - "a polylogarithmic competitive algorithm for the k server problem"
    - "13 9 approximation for graphic tsp"

Connected through hyperedge HE-8 (induced by source paper "on the integrality ratio of the subtour lp for euclidean tsp"):
  with members:
    - "on the integrality gap of the subtour lp for the 1 2 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)