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: "formula transformers and combinatorial test generators for propositional intuitionistic theorem provers"
  Abstract: We develop combinatorial test generation algorithms for progressively more powerful theorem provers, covering formula languages ranging from the implicational fragment of intuitionistic logic to full intuitionistic propositional logic. Our algorithms support exhaustive and random generators for formulas of these logics. #R##N#To provide known-to-be-provable formulas, via the Curry-Howard formulas-as-types correspondence, we use generators for typable lambda terms and combinator expressions. Besides generators for several classes of formulas, we design algorithms that restrict formula generation to canonical representatives among equiprovable formulas and introduce program transformations that reduce formulas to equivalent formulas of a simpler structure. The same transformations, when applied in reverse, create harder formulas that can catch soundness or incompleteness bugs. #R##N#To test the effectiveness of the testing framework itself, we describe use cases for deriving lightweight theorem provers for several of these logics and for finding bugs in known theorem provers. Our Prolog implementation available at: this https URL and a subset of formula generators and theorem provers, implemented in Python is available at: this https URL. #R##N#Keywords: term and formula generation algorithms, Prolog-based theorem provers, formulas-as-types, type inference and type inhabitation, combinatorial testing, finding bugs in 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)