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: "characterising testing preorders for finite probabilistic processes"
  Abstract: In 1992 Wang & Larsen extended the may- and must preorders of De Nicola and#N#Hennessy to processes featuring probabilistic as well as nondeterministic#N#choice. They concluded with two problems that have remained open throughout the#N#years, namely to find complete axiomatisations and alternative#N#characterisations for these preorders. This paper solves both problems for#N#finite processes with silent moves. It characterises the may preorder in terms#N#of simulation, and the must preorder in terms of failure simulation. It also#N#gives a characterisation of both preorders using a modal logic. Finally it#N#axiomatises both preorders over a probabilistic version of CSP.

Connected through hyperedge HE-1 (induced by source paper "ensuring liveness properties of distributed systems open problems"):
  with members:
    - "progress justness and fairness"
    - "reward testing equivalences for processes"
    - "justness a completeness criterion for capturing liveness properties"
    - "analysing mutual exclusion using process algebra with signals"
    - "lean and full congruence formats for recursion"
    - "structure preserving bisimilarity supporting an operational petri net semantics of ccsp"
    - "ccs it s not fair fair schedulers cannot be implemented in ccs like languages even under progress and certain fairness assumptions"
    - "progress fairness and justness in process algebra"

Connected through hyperedge HE-2 (induced by source paper "reward testing equivalences for processes"):
  with members:
    - "lean and full congruence formats for recursion"
    - "ensuring liveness properties of distributed systems a research agenda"
    - "progress fairness and justness in process algebra"
    - "on the axiomatizability of impossible futures"
    - "the coarsest precongruences respecting safety and liveness properties"

Connected through hyperedge HE-3 (induced by source paper "graded monads and graded logics for the linear time branching time spectrum"):
  with members:
    - "convex language semantics for nondeterministic probabilistic automata"
    - "coalgebraic trace semantics via forgetful logics"
    - "a linear time branching time spectrum of behavioral specification theories"
    - "automata theory in nominal sets"
    - "coalgebraic trace semantics for continuous probabilistic transition systems"
    - "sound and complete axiomatizations of coalgebraic language equivalence"
    - "from branching to linear time coalgebraically"
    - "generalizing determinization from automata to coalgebras"

Connected through hyperedge HE-4 (induced by source paper "trace and testing metrics on nondeterministic probabilistic processes"):
  with members:
    - "sos based modal decomposition on nondeterministic probabilistic processes"
    - "logical characterization of trace metrics"
    - "logical characterization of bisimulation metrics"
    - "revisiting trace and testing equivalences for nondeterministic and probabilistic processes"
    - "the spectrum of strong behavioral equivalences for nondeterministic and probabilistic processes"

Connected through hyperedge HE-5 (induced by source paper "mixed powerdomains for probability and nondeterminism"):
  with members:
    - "on the equivalence of state transformer semantics and predicate transformer semantics"

Connected through hyperedge HE-6 (induced by source paper "logical characterization of bisimulation metrics"):
  with members:
    - "divide and congruence ii from decomposition of modal formulas to preservation of delay and weak bisimilarity"
    - "modal characterisations of behavioural pseudometrics"
    - "topologies of stochastic markov models computational aspects"
    - "probabilistic bisimulation naturally on distributions"
    - "fixed point characterization of compositionality properties of probabilistic processes combinators"
    - "when equivalence and bisimulation join forces in probabilistic automata"
    - "continuous markovian logics axiomatization and quantified metatheory"
    - "logical metric and algorithmic characterisations of probabilistic bisimulation"

Connected through hyperedge HE-7 (induced by source paper "revisiting trace and testing equivalences for nondeterministic and probabilistic processes"):
  with members:
    - "bisimilarity and behaviour preserving reconfigurations of open petri nets"

Connected through hyperedge HE-8 (induced by source paper "the spectrum of strong behavioral equivalences for nondeterministic and probabilistic processes"):
  with members:
    - "revisiting trace and testing equivalences for nondeterministic and probabilistic processes"
    - "bisimulations meet pctl equivalences for probabilistic automata"
    - "computing distances between probabilistic automata"
    - "game refinement relations and metrics"

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)