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 complexity of verifying regular properties on flat counter systems"
  Abstract: Among the approximation methods for the verification of counter systems, one of them consists in model-checking their flat unfoldings. Unfortunately, the complexity characterization of model-checking problems for such operational models is not always well studied except for reachability queries or for Past LTL. In this paper, we characterize the complexity of model-checking problems on flat counter systems for the specification languages including first-order logic, linear mu-calculus, infinite automata, and related formalisms. Our results span different complexity classes (mainly from PTime to PSpace) and they apply to languages in which arithmetical constraints on counter values are systematically allowed. As far as the proof techniques are concerned, we provide a uniform approach that focuses on the main issues.

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"
    - "taming past ltl and 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 "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"
    - "invariant generation through strategy iteration in succinctly represented control flow graphs"
    - "taming past ltl and flat counter systems"

Connected through hyperedge HE-3 (induced by source paper "taming past ltl and flat counter systems"):
  with members:
    - "integer vector addition systems with states"
    - "safety problems are np complete for flat integer programs with octagonal loops"

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)