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: "on the freeze quantifier in constraint ltl decidability and complexity"
  Abstract: Constraint LTL, a generalization of LTL over Presburger constraints, is often used as a formal language to specify the behavior of operational models with constraints. The freeze quantifier can be part of the language, as in some real-time logics, but this variable-binding mechanism is quite general and ubiquitous in many logical languages (first-order temporal logics, hybrid logics, logics for sequence diagrams, navigation logics, etc.). We show that Constraint LTL over the simple domain   augmented with the freeze operator is undecidable which is a surprising result regarding the poor language for constraints (only equality tests). Many versions of freeze-free constraint LTL are decidable over domains with qualitative predicates and our undecidability result actually establishes /spl Sigma//sub 1//sup 1/ -completeness. On the positive side, we provide complexity results when the domain is finite (EXPSPACE-completeness) or when the formulae are flat in a sense introduced in the paper.

Connected through hyperedge HE-1 (induced by source paper "modular path queries with arithmetic"):
  with members:
    - "querying best paths in graph databases"
    - "g core a core for future graph query languages"
    - "expressive path queries on graph with data"
    - "reachability in two dimensional vector addition systems with states is pspace complete"

Connected through hyperedge HE-2 (induced by source paper "complexity results on register pushdown automata"):
  with members:
    - "bottom up automata on data trees and vertical xpath"
    - "alternating register automata on finite words and trees"

Connected through hyperedge HE-3 (induced by source paper "scalar and vectorial mu calculus with atoms"):
  with members:
    - "modal logics for nominal transition systems"
    - "reasoning about data repetitions with counter systems"
    - "smt solving for functional programming over infinite structures"
    - "automata theory in nominal sets"
    - "alternating register automata on finite words and trees"
    - "alternating automata on data trees and xpath satisfiability"
    - "ltl with the freeze quantifier and register automata"

Connected through hyperedge HE-4 (induced by source paper "model checking flat freeze ltl on one counter automata"):
  with members:
    - "reachability in two clock timed automata is pspace complete"
    - "ltl with the freeze quantifier and register automata"

Connected through hyperedge HE-5 (induced by source paper "synchronizing data words for register automata"):
  with members:
    - "complexity hierarchies beyond elementary"
    - "timed pushdown automata revisited"
    - "alternating register automata on finite words and trees"
    - "ackermannian and primitive recursive bounds with dickson s lemma"
    - "ltl with the freeze quantifier and register automata"

Connected through hyperedge HE-6 (induced by source paper "the complexity of flat freeze ltl"):
  with members:
    - "what s decidable about parametric timed automata"
    - "simulation problems over one counter nets"
    - "shortest paths in one counter systems"
    - "path checking for mtl and tptl over data words"
    - "ltl with the freeze quantifier and register automata"

Connected through hyperedge HE-7 (induced by source paper "quantitative regular expressions for arrhythmia detection algorithms"):
  with members:
    - "montre a tool for monitoring timed regular expressions"
    - "regular combinators for string transformations"

Connected through hyperedge HE-8 (induced by source paper "on freeze ltl with ordered attributes"):
  with members:
    - "reasoning about data repetitions with counter systems"
    - "complexity hierarchies beyond elementary"
    - "demystifying reachability in vector addition systems"
    - "ordered navigation on multi attributed data words"
    - "the power of priority channel systems"
    - "alternating register automata on finite words and trees"
    - "temporal logics on words with multiple data values"
    - "ltl with the freeze quantifier and register automata"

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.LO(Logic in Computer Science)