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: "extensional higher order logic programming"
  Abstract: We propose a purely extensional semantics for higher-order logic programming. In this semantics program predicates denote sets of ordered tuples, and two predicates are equal iff they are equal as sets. Moreover, every program has a unique minimum Herbrand model which is the greatest lower bound of all Herbrand models of the program and the least fixed-point of an immediate consequence operator. We also propose an SLD-resolution proof procedure which is proven sound and complete with respect to the minimum model semantics. In other words, we provide a purely extensional theoretical framework for higher-order logic programming which generalizes the familiar theory of classical (first-order) logic programming.

Connected through hyperedge HE-1 (induced by source paper "hochc a refutationally complete and semantically invariant system of higher order logic modulo theories"):
  with members:
    - "defunctionalization of higher order constrained horn clauses"
    - "language and proofs for higher order smt work in progress"
    - "the universal fragment of presburger arithmetic with unary uninterpreted predicates is undecidable"

Connected through hyperedge HE-2 (induced by source paper "the expressive power of higher order datalog"):
  with members:
    - "approximation fixpoint theory and the well founded semantics of higher order logic programs"

Connected through hyperedge HE-3 (induced by source paper "approximation fixpoint theory and the well founded semantics of higher order logic programs"):
  with members:
    - "extensional semantics for higher order logic programs with negation"
    - "an analysis of the equational properties of the well founded fixed point"
    - "equivalence of two fixed point semantics for definitional higher order logic programs"
    - "a fixed point theorem for non monotonic functions"
    - "minimum model semantics for extensional higher order logic programming with negation"

Connected through hyperedge HE-4 (induced by source paper "predicate specialization for definitional higher order logic programs"):
  with members:
    - "xsb extending prolog with tabled logic programming"

Connected through hyperedge HE-5 (induced by source paper "extensional semantics for higher order logic programs with negation"):
  with members:
    - "an analysis of the equational properties of the well founded fixed point"
    - "equivalence of two fixed point semantics for definitional higher order logic programs"
    - "minimum model semantics for extensional higher order logic programming with negation"
    - "minimum model semantics for logic programs with negation as failure"

Connected through hyperedge HE-6 (induced by source paper "equivalence of two fixed point semantics for definitional higher order logic programs"):
  with members:
    - "minimum model semantics for extensional higher order logic programming with negation"

Connected through hyperedge HE-7 (induced by source paper "a fixed point theorem for non monotonic functions"):
  with members:
    - "minimum model semantics for extensional higher order logic programming with negation"
    - "splitting an operator algebraic modularity results for logics with fixpoint semantics"
    - "minimum model semantics for logic programs with negation as failure"

Connected through hyperedge HE-8 (induced by source paper "minimum model semantics for extensional higher order logic programming with negation"):
  with members:
    - "a fixed point theorem for non monotonic functions"
    - "linear logic based analysis of constraint handling rules with disjunction"
    - "minimum model semantics for logic programs with negation as failure"

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)