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: "abstract gringo"
  Abstract: This paper defines the syntax and semantics of the input language of the ASP grounder GRINGO. The definition covers several constructs that were not discussed in earlier work on the semantics of that language, including intervals, pools, division of integers, aggregates with non-numeric values, and lparse-style aggregate expressions. The definition is abstract in the sense that it disregards some details related to representing programs by strings of ASCII characters. It serves as a specification for GRINGO from Version 4.5 on.

Connected through hyperedge HE-1 (induced by source paper "asp core 2 input language format"):
  with members:
    - "relating two dialects of answer set programming"
    - "routing driverless transport vehicles in car assembly with answer set programming"
    - "rewriting recursive aggregates in answer set programming back to monotonicity"
    - "vicious circle principle and logic programs with aggregates"
    - "the third open answer set programming competition"
    - "unfounded sets and well founded semantics of answer set programs with aggregates"
    - "well founded and stable semantics of logic programs with aggregates"

Connected through hyperedge HE-2 (induced by source paper "strong equivalence and program s structure in arguing essential equivalence between logic programs"):
  with members:
    - "first order modular logic programs and their conservative extensions"
    - "lpopt a rule optimization tool for answer set programming"
    - "modularity aspects of disjunctive stable models"
    - "a common view on strong uniform and other notions of equivalence in answer set programming"
    - "weight constraints as nested expressions"

Connected through hyperedge HE-3 (induced by source paper "relating two dialects of answer set programming"):
  with members:
    - "vicious circle principle and logic programs with aggregates"

Connected through hyperedge HE-4 (induced by source paper "a trajectory calculus for qualitative spatial reasoning using answer set programming"):
  with members:
    - "non monotonic spatial reasoning with answer set programming modulo theories"

Connected through hyperedge HE-5 (induced by source paper "program completionin the input language of gringo"):
  with members:
    - "lloyd topor completion and general stable models"

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)