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: "alpaga a tool for solving parity games with imperfect information"
  Abstract: Alpaga is a solver for two-player parity games with imperfect information. Given the description of a game, it determines whether the first player can ensure to win and, if so, it constructs a winning strategy. The tool provides a symbolic implementation of a recent algorithm based on antichains.

Connected through hyperedge HE-1 (induced by source paper "a comparison of bdd based parity game solvers"):
  with members:
    - "solving parity games using an automata based algorithm"
    - "oink an implementation and evaluation of modern parity game solvers"
    - "an ordered approach to solving parity games in quasi polynomial time and quasi linear space"
    - "succinct progress measures for solving parity games"
    - "a delayed promotion policy for parity games"
    - "benchmarks for parity games"
    - "the fixpoint iteration algorithm for parity games"
    - "zielonka s recursive algorithm dull weak and solitaire games and tighter bounds"

Connected through hyperedge HE-2 (induced by source paper "satisfiability based methods for reactive synthesis from safety specifications"):
  with members:
    - "the second reactive synthesis competition syntcomp 2015"
    - "incremental qbf solving"
    - "abssynthe abstract synthesis from succinct safety specifications"
    - "synthesizing multiple boolean functions using interpolation on a single proof"
    - "algorithms for omega regular games with imperfect information"

Connected through hyperedge HE-3 (induced by source paper "looking at mean payoff through foggy windows"):
  with members:
    - "looking at mean payoff and total payoff through windows"
    - "antichains for the automata based approach to model checking"
    - "algorithms for omega regular games with imperfect information"

Connected through hyperedge HE-4 (induced by source paper "a game theoretic approach for synthesizing fault tolerant embedded systems"):
  with members:
    - "modeling and verification for timing satisfaction of fault tolerant systems with finiteness"

Connected through hyperedge HE-5 (induced by source paper "qualitative concurrent stochastic games with imperfect information"):
  with members:
    - "algorithms for omega regular games with imperfect information"

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)