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: "formalising the pi calculus using nominal logic"
  Abstract: We formalise the pi-calculus using the nominal datatype package, based on#N#ideas from the nominal logic by Pitts et al., and demonstrate an implementation#N#in Isabelle/HOL. The purpose is to derive powerful induction rules for the#N#semantics in order to conduct machine checkable proofs, closely following the#N#intuitive arguments found in manual proofs. In this way we have covered many of#N#the standard theorems of bisimulation equivalence and congruence, both late and#N#early, and both strong and weak in a uniform manner. We thus provide one of the#N#most extensive formalisations of a process calculus ever done inside a theorem#N#prover.#N#  A significant gain in our formulation is that agents are identified up to#N#alpha-equivalence, thereby greatly reducing the arguments about bound names.#N#This is a normal strategy for manual proofs about the pi-calculus, but that#N#kind of hand waving has previously been difficult to incorporate smoothly in an#N#interactive theorem prover. We show how the nominal logic formalism and its#N#support in Isabelle accomplishes this and thus significantly reduces the tedium#N#of conducting completely formal proofs. This improves on previous work using#N#weak higher order abstract syntax since we do not need extra assumptions to#N#filter out exotic terms and can keep all arguments within a familiar#N#first-order logic.

Connected through hyperedge HE-1 (induced by source paper "rule formats for nominal process calculi"):
  with members:
    - "modal logics for nominal transition systems"

Connected through hyperedge HE-2 (induced by source paper "unique solutions of contractions ccs and their hol formalisation"):
  with members:
    - "divergence and unique solution of equations"

Connected through hyperedge HE-3 (induced by source paper "proof relevant pi calculus a constructive account of concurrency and causality"):
  with members:
    - "causally consistent dynamic slicing"
    - "proof relevant pi calculus"

Connected through hyperedge HE-4 (induced by source paper "on the expressiveness of intensional communication"):
  with members:
    - "a concurrent pattern calculus"
    - "an intensional concurrent faithful encoding of turing machines"
    - "expressiveness via intensionality and concurrency"
    - "musings on encodings and expressiveness"
    - "psi calculi a framework for mobile processes with nominal data and logic"
    - "multiparty symmetric sum types"
    - "comparing the expressive power of the synchronous and asynchronous pi calculi"

Connected through hyperedge HE-5 (induced by source paper "a concurrent pattern calculus"):
  with members:
    - "musings on encodings and expressiveness"
    - "psi calculi a framework for mobile processes with nominal data and logic"

Connected through hyperedge HE-6 (induced by source paper "psi calculi a framework for mobile processes with nominal data and logic"):
  with members:
    - "a fully abstract symbolic semantics for psi calculi"
    - "relating two standard notions of secrecy"

Connected through hyperedge HE-7 (induced by source paper "proof search specifications of bisimulation and modal logics for the pi calculus"):
  with members:
    - "induction and co induction in sequent calculus"
    - "the bedwyr system for model checking over syntactic expressions"
    - "focusing and polarization in intuitionistic logic"
    - "natural deduction as higher order resolution"
    - "reasoning with higher order abstract syntax in a logical framework"
    - "isabelle the next 700 theorem provers"

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)