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: "formalization of abstract state transition systems for sat"
  Abstract: We present a formalization of modern SAT solvers and their properties in a#N#form of abstract state transition systems. SAT solving procedures are described#N#as transition relations over states that represent the values of the solver's#N#global variables. Several different SAT solvers are formalized, including both#N#the classical DPLL procedure and its state-of-the-art successors. The#N#formalization is made within the Isabelle/HOL system and the total correctness#N#(soundness, termination, completeness) is shown for each presented system (with#N#respect to a simple notion of satisfiability that can be manually checked). The#N#systems are defined in a general way and cover procedures used in a wide range#N#of modern SAT solvers. Our formalization builds up on the previous work on#N#state transition systems for SAT, but it gives machine-verifiable proofs,#N#somewhat more general specifications, and weaker assumptions that ensure the#N#key correctness properties. The presented proofs of formal correctness of the#N#transition systems can be used as a key building block in proving correctness#N#of SAT solvers by using other verification approaches.

Connected through hyperedge HE-1 (induced by source paper "efficient certified resolution proof checking"):
  with members:
    - "efficient certified rat verification"
    - "the drat format and drat trim checker"
    - "solving and verifying the boolean pythagorean triples problem via cube and conquer"
    - "formalizing size optimal sorting networks extracting a certified proof checker"
    - "optimizing a certified proof checker for a large scale computer generated proof"
    - "computer aided proof of erdos discrepancy properties"
    - "a framework for the verification of certifying computations"
    - "co c e spheres and cells in computable metric spaces"

Connected through hyperedge HE-2 (induced by source paper "efficient certified rat verification"):
  with members:
    - "efficient certified resolution proof checking"
    - "the drat format and drat trim checker"
    - "solving and verifying the boolean pythagorean triples problem via cube and conquer"

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)