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 multicore tool for constraint solving"
  Abstract: *** To appear in IJCAI 2015 proceedings *** In Constraint Programming (CP), a portfolio solver uses a variety of different solvers for solving a given Constraint Satisfaction / Optimization Problem. In this paper we introduce sunny-cp2: the first parallel CP portfolio solver that enables a dynamic, cooperative, and simultaneous execution of its solvers in a multicore setting. It incorporates state-of-the-art solvers, providing also a usable and configurable framework. Empirical results are very promising. sunny-cp2 can even outperform the performance of the oracle solver which always selects the best solver of the portfolio for a given problem.

Connected through hyperedge HE-1 (induced by source paper "a review of literature on parallel constraint solving"):
  with members:
    - "parallel strategies selection"
    - "solving and verifying the boolean pythagorean triples problem via cube and conquer"
    - "hordesat a massively parallel portfolio sat solver"
    - "the shape of the search tree for the maximum clique problem and the implications for parallel branch and bound"
    - "proteus a hierarchical portfolio of solvers and transformations"
    - "asymmetric distributed constraint optimization problems"
    - "algorithm selection for combinatorial search problems a survey"
    - "distributed solving through model splitting"

Connected through hyperedge HE-2 (induced by source paper "constraint programming for flexible service function chaining deployment"):
  with members:
    - "network function virtualization state of the art and research challenges"
    - "disco distributed multi domain sdn controllers"

Connected through hyperedge HE-3 (induced by source paper "sunny cp and the minizinc challenge"):
  with members:
    - "sunny a lazy portfolio approach for constraint solving"
    - "an enhanced features extractor for a portfolio of constraint solvers"
    - "algorithm runtime prediction methods evaluation"
    - "algorithm selection for combinatorial search problems a survey"

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.AI(Artificial Intelligence)