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: "taming past ltl and flat counter systems"
  Abstract: Reachability and LTL model-checking problems for flat counter systems are known to be decidable but whereas the reachability problem can be shown in NP, the best known complexity upper bound for the latter problem is made of a tower of several exponentials. Herein, we show that the problem is only NP-complete even if LTL admits past-time operators and arithmetical constraints on counters. Actually, the NP upper bound is shown by adequately combining a new stuttering theorem for Past LTL and the property of small integer solutions for quantifier-free Presburger formulae. Other complexity results are proved, for instance for restricted classes of flat counter systems.

Connected through hyperedge HE-1 (induced by source paper "verification of flat fifo systems"):
  with members:
    - "verifying asynchronous interactions via communicating session automata"
    - "model checking counting temporal logics on flat structures"
    - "synchronizability of communicating finite state machines is not decidable"
    - "structurally cyclic petri nets"
    - "on the complexity of verifying regular properties on flat counter systems"
    - "forward analysis for wsts part ii complete wsts"
    - "a perfect model for bounded verification"

Connected through hyperedge HE-2 (induced by source paper "register games"):
  with members:
    - "alternating weak automata from universal trees"
    - "universal trees grow inside separating automata quasi polynomial lower bounds for parity games"
    - "robust exponential worst cases for divide et impera algorithms for parity games"
    - "succinct progress measures for solving parity games"

Connected through hyperedge HE-3 (induced by source paper "flat model checking for counting ltl using quantifier free presburger arithmetic"):
  with members:
    - "model checking counting temporal logics on flat structures"
    - "lower bound on weights of large degree threshold functions"

Connected through hyperedge HE-4 (induced by source paper "how hard is it to verify flat affine counter systems with the finite monoid property"):
  with members:
    - "reachability in two dimensional vector addition systems with states is pspace complete"
    - "a concurrent pattern calculus"
    - "subclasses of presburger arithmetic and the weak exp hierarchy"
    - "deciding conditional termination"
    - "on the complexity of verifying regular properties on flat counter systems"
    - "invariant generation through strategy iteration in succinctly represented control flow graphs"

Connected through hyperedge HE-5 (induced by source paper "interprocedural reachability for flat integer programs"):
  with members:
    - "underapproximation of procedure summaries for integer programs"
    - "safety problems are np complete for flat integer programs with octagonal loops"
    - "the reachability problem for vector addition systems with a stack is not elementary"
    - "an extension of parikh s theorem beyond idempotence"
    - "approximating petri net reachability along context free traces"
    - "the octagon abstract domain"

Connected through hyperedge HE-6 (induced by source paper "forward analysis and model checking for trace bounded wsts"):
  with members:
    - "complexity hierarchies beyond elementary"
    - "reachability in two dimensional vector addition systems with states is pspace complete"
    - "interprocedural reachability for flat integer programs"
    - "algorithmic verification of asynchronous programs"
    - "forward analysis for wsts part ii complete wsts"
    - "ackermannian and primitive recursive bounds with dickson s lemma"
    - "multiply recursive upper bounds with higman s lemma"
    - "on selective unboundedness of vass"

Connected through hyperedge HE-7 (induced by source paper "on selective unboundedness of vass"):
  with members:
    - "small vertex cover makes petri net coverability and boundedness easier"
    - "parikh images of regular languages complexity and applications"

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)