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: "a bi directional refinement algorithm for the calculus of co inductive constructions"
  Abstract: The paper describes the renement algorithm for the Calculus of (Co)Inductive Constructions (CIC) implemented in the interactive theorem prover Matita. The renement algorithm is in charge of giving a meaning to the terms, types and proof terms directly written by the user or generated by using tactics, decision procedures or general automation. The terms are written in an \external syntax" meant to be user friendly that allows omission of information, untyped binders and a certain liberal use of user dened sub-typing. The rener modies the terms to obtain related well typed terms in the internal syntax understood by the kernel of the ITP. In particular, it acts as a type inference algorithm when all the binders are untyped. The proposed algorithm is bi-directional: given a term in external syntax and a type expected for the term, it propagates as much typing information as possible towards the leaves of the term. Traditional mono-directional algorithms, instead, proceed in a bottom- up way by inferring the type of a sub-term and comparing (unifying) it with the type expected by its context only at the end. We propose some novel bi-directional rules for CIC that are particularly eective. Among the benets of bi-directionality we have better error message reporting and better inference of dependent types. Moreover, thanks to bi-directionality, the coercion system for sub-typing is more eective and type inference generates simpler unication problems that are more likely to be solved by the inherently incomplete higher order unication algorithms implemented. Finally we introduce in the external syntax the notion of vector of placeholders that enables to omit at once an arbitrary number of arguments. Vectors of placeholders allow a trivial implementation of implicit arguments and greatly simplify the implementation of primitive and simple tactics.

Connected through hyperedge HE-1 (induced by source paper "a type checker for a logical framework with union and intersection types"):
  with members:
    - "non idempotent intersection types in logical form"
    - "the delta calculus syntax and types"
    - "the delta framework"
    - "refinement types for logical frameworks and their interpretation as proof irrelevance"

Connected through hyperedge HE-2 (induced by source paper "deciding univariate polynomial problems using untrusted certificates in isabelle hol"):
  with members:
    - "formal verification of nonlinear inequalities with taylor interval approximations"

Connected through hyperedge HE-3 (induced by source paper "advances in property based testing for alpha prolog"):
  with members:
    - "a framework for proof certificates in finite state exploration"
    - "general bindings and alpha equivalence in nominal isabelle"
    - "coinductive big step operational semantics"
    - "the bedwyr system for model checking over syntactic expressions"
    - "nominal logic programming"
    - "higher order pattern complement and the strict λ calculus"

Connected through hyperedge HE-4 (induced by source paper "canonicity for cubical type theory"):
  with members:
    - "cubical type theory a constructive interpretation of the univalence axiom"
    - "computational higher type theory i abstract cubical realizability"
    - "computational higher type theory ii dependent cubical realizability"
    - "the independence of markov s principle in type theory"
    - "on irrelevance and algorithmic equality in predicative type theory"

Connected through hyperedge HE-5 (induced by source paper "property based polynomial invariant generation using sums of squares optimization"):
  with members:
    - "a sums of squares extension of policy iterations"
    - "coupling policy iteration with semi definite relaxation to compute accurate numerical invariants in static analysis"
    - "exact safety verification of hybrid systems using sums of squares representation"

Connected through hyperedge HE-6 (induced by source paper "on the path width of integer linear programming"):
  with members:
    - "model checking of ordered multi pushdown automata"
    - "reachability analysis of communicating pushdown systems"
    - "a perfect model for bounded verification"

Connected through hyperedge HE-7 (induced by source paper "zenoness for timed pushdown automata"):
  with members:
    - "reachability analysis of communicating pushdown systems"
    - "efficient emptiness check for timed b uchi automata extended version"
    - "pushdown timed automata a binary reachability characterization and safety verification"

Connected through hyperedge HE-8 (induced by source paper "zenoness for timed pushdown automata"):
  with members:
    - "reachability analysis of communicating pushdown systems"
    - "efficient emptiness check for timed b uchi automata extended version"
    - "pushdown timed automata a binary reachability characterization and safety verification"

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)