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: "a 7 9 approximation algorithm for the maximum traveling salesman problem"
  Abstract: We give a deterministic combinatorial 7/9-approximation algorithm for the symmetric maximum traveling salesman problem.

Connected through hyperedge HE-1 (induced by source paper "utilitarians without utilities maximizing social welfare for graph problems using only ordinal preferences full version"):
  with members:
    - "truthful mechanisms for matching and clustering in an ordinal world"
    - "metric distortion of social choice rules lower bounds and fairness properties"
    - "randomized social choice functions under metric preferences"

Connected through hyperedge HE-2 (induced by source paper "a 4 5 approximation algorithm for the maximum traveling salesman problem"):
  with members:
    - "better approximation algorithms for maximum asymmetric traveling salesman and shortest superstring"
    - "the geometric maximum traveling salesman problem"

Connected through hyperedge HE-3 (induced by source paper "maximum atsp with weights zero and one via half edges"):
  with members:
    - "better approximation algorithms for maximum asymmetric traveling salesman and shortest superstring"

Connected through hyperedge HE-4 (induced by source paper "better approximation algorithms for maximum asymmetric traveling salesman and shortest superstring"):
  with members:
    - "lyndon words and short superstrings"

Connected through hyperedge HE-5 (induced by source paper "approximability of connected factors"):
  with members:
    - "finding small separators in linear time via treewidth reduction"

Connected through hyperedge HE-6 (induced by source paper "applications of discrepancy theory in multiobjective approximation"):
  with members:
    - "on approximating multi criteria tsp"
    - "approximation algorithms for multi criteria traveling salesman problems"
    - "on approximating restricted cycle covers"

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.GT(Computer Science and Game Theory)