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: "unifying theories of time with generalised reactive processes"
  Abstract: Abstract   Hoare and He's theory of reactive processes provides a unifying foundation for the formal semantics of concurrent and reactive languages. Though highly applicable, their theory is limited to models that can express event histories as discrete sequences. In this paper, we show how their theory can be generalised by using an abstract trace algebra. We show how the algebra, notably, allows us to consider continuous-time traces and thereby facilitate models of hybrid systems. We then use this algebra to reconstruct the theory of reactive processes in our generic setting, and prove characteristic laws for sequential and parallel processes, all of which have been mechanically verified in the Isabelle/HOL proof assistant.

Connected through hyperedge HE-1 (induced by source paper "unifying semantic foundations for automated verification tools in isabelle utp"):
  with members:
    - "differential hoare logics and refinement calculi for hybrid systems with isabelle hol"
    - "calculational verification of reactive programs with reactive relations and kleene algebra"
    - "automating verification of state machines with reactive designs and isabelle utp"
    - "robotics and integrated formal methods necessity meets opportunity"
    - "unifying theories of reactive design contracts"
    - "profunctor optics modular data accessors"

Connected through hyperedge HE-2 (induced by source paper "calculational verification of reactive programs with reactive relations and kleene algebra"):
  with members:
    - "unifying theories of reactive design contracts"
    - "the refinement calculus of reactive systems"

Connected through hyperedge HE-3 (induced by source paper "automating verification of state machines with reactive designs and isabelle utp"):
  with members:
    - "calculational verification of reactive programs with reactive relations and kleene algebra"
    - "unifying theories of reactive design contracts"

Connected through hyperedge HE-4 (induced by source paper "unifying theories of reactive design contracts"):
  with members:
    - "designing a semantic model for a wide spectrum language with concurrency"
    - "an algebra of synchronous atomic steps"
    - "generalised rely guarantee concurrency an algebraic foundation"

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)