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: "the alldifferent constraint a survey"
  Abstract: The constraint of difference is known to the constraint pro- gramming community since Lauriere introduced Alice (11) in 1978. Since then, several solving strategies have been designed for this constraint. In this paper we give both a practical overview and an abstract comparison of these different strategies.

Connected through hyperedge HE-1 (induced by source paper "xcsp3 an integrated format for benchmarking combinatorial constrained problems"):
  with members:
    - "short and long supports for constraint propagation"
    - "the seqbin constraint revisited"
    - "stochastic constraint programming"
    - "slide a useful special case of the cardpath constraint"
    - "decompositions of grammar constraints"
    - "finite domain bounds consistency revisited"

Connected through hyperedge HE-2 (induced by source paper "boolean equi propagation for concise and efficient sat encodings of combinatorial problems"):
  with members:
    - "compiling finite domain constraints to sat with bee"
    - "boolean equi propagation for optimized sat encoding"
    - "optimal base encodings for pseudo boolean constraints"
    - "circuit complexity and decompositions of global constraints"
    - "logic programming with satisfiability"

Connected through hyperedge HE-3 (induced by source paper "the tractability of csp classes defined by forbidden patterns"):
  with members:
    - "a dichotomy for 2 constraint forbidden csp patterns"
    - "hybrid tractability of valued constraint problems"
    - "tractable hypergraph properties for constraint satisfaction and conjunctive queries"
    - "hypertree decompositions and tractable queries"

Connected through hyperedge HE-4 (induced by source paper "machine learning for constraint solver design a case study for the alldifferent constraint"):
  with members:
    - "practical graph isomorphism ii"
    - "constraint solvers an empirical evaluation of design decisions"
    - "satzilla portfolio based algorithm selection for sat"

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.PL(Programming Languages)