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: "proving soundness of extensional normal form bisimilarities"
  Abstract: Normal-form bisimilarity is a simple, easy-to-use behavioral equivalence that relates terms in lambda-calculi by decomposing their normal forms into bisimilar subterms. Besides, they allow for powerful up-to techniques, such as bisimulation up to context, which simplify bisimulation proofs even further. However, proving soundness of these relations becomes complicated in the presence of eta-expansion and usually relies on ad hoc proof methods which depend on the language. In this paper we propose a more systematic proof method to show that an extensional normal-form bisimilarity along with its corresponding bisimulation up to context are sound. We illustrate our technique with three calculi: the call-by-value lambda-calculus, the call-by-value lambda-calculus with the delimited-control operators shift and reset, and the call-by-value lambda-calculus with the abortive control operators call/cc and abort. In the first two cases, there was previously no sound bisimulation up to context validating the eta-law, whereas no theory of normal-form bisimulations for the calculus of abortive control has been presented before. Our results have been fully formalized in the Coq proof assistant.

Connected through hyperedge HE-1 (induced by source paper "bisimulations for delimited control operators"):
  with members:
    - "environmental bisimulations for delimited control operators with dynamic prompt generation"
    - "proving termination of evaluation for system f with control operators"
    - "environmental bisimulations for delimited control operators"
    - "normal form bisimulations for delimited control operators"
    - "applicative bisimulations for delimited control operators"
    - "an operational foundation for delimited continuations in the cps hierarchy"
    - "delimited continuations in natural language quantification and polarity sensitivity"

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)