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 natural counting of lambda terms"
  Abstract: We study the sequences of numbers corresponding to lambda terms of given sizes, where the size is this of lambda terms with de Bruijn indices in a very natural model where all the operators have size 1. For plain lambda terms, the sequence corresponds to two families of binary trees for which we exhibit bijections. We study also the distribution of normal forms, head normal forms and strongly normalizing terms. In particular we show that strongly normalizing terms are of density 0 among plain terms.

Connected through hyperedge HE-1 (induced by source paper "formula transformers and combinatorial test generators for propositional intuitionistic theorem provers"):
  with members:
    - "modality definition synthesis for epistemic intuitionistic logic via a theorem prover"
    - "on uniquely closable and uniquely typable skeletons of lambda terms"
    - "a hiking trip through the orders of magnitude deriving efficient generators for closed simply typed lambda terms and normal forms"
    - "random generation of closed simply typed lambda terms a synergy between logic programming and boltzmann samplers"
    - "counting and generating terms in the binary lambda calculus extended version"
    - "a logic programming playground for lambda terms combinators types and tree based arithmetic computations"
    - "counting and generating lambda terms"

Connected through hyperedge HE-2 (induced by source paper "combinatorics of explicit substitutions"):
  with members:
    - "counting environments and closures"
    - "normal order reduction grammars"
    - "combinatorics of lambda terms a natural approach"
    - "leftmost outermost beta reduction is invariant indeed"
    - "counting and generating terms in the binary lambda calculus extended version"
    - "modular complexity analysis for term rewriting"
    - "counting and generating lambda terms"
    - "on constructor rewrite systems and the lambda calculus"

Connected through hyperedge HE-3 (induced by source paper "on the enumeration of closures and environments with an application to random generation"):
  with members:
    - "combinatorics of explicit substitutions"
    - "normal order reduction grammars"
    - "leftmost outermost beta reduction is invariant indeed"
    - "counting and generating terms in the binary lambda calculus extended version"
    - "on constructor rewrite systems and the lambda calculus"
    - "smoothed analysis of algorithms why the simplex algorithm usually takes polynomial time"

Connected through hyperedge HE-4 (induced by source paper "quantitative aspects of linear and affine closed lambda terms"):
  with members:
    - "linear lambda terms as invariants of rooted trivalent maps"
    - "counting and generating terms in the binary lambda calculus extended version"
    - "counting isomorphism classes of β normal linear lambda terms"
    - "a correspondence between rooted planar maps and normal planar lambda terms"
    - "boltzmann samplers for random generation of lambda terms"
    - "counting and generating lambda terms"
    - "on counting untyped lambda terms"
    - "how big is bci fragment of bck logic"

Connected through hyperedge HE-5 (induced by source paper "a hiking trip through the orders of magnitude deriving efficient generators for closed simply typed lambda terms and normal forms"):
  with members:
    - "counting and generating terms in the binary lambda calculus extended version"
    - "a logic programming playground for lambda terms combinators types and tree based arithmetic computations"
    - "boltzmann samplers for random generation of lambda terms"
    - "counting and generating lambda terms"

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)