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: "formalizing size optimal sorting networks extracting a certified proof checker"
  Abstract: Since the proof of the four color theorem in 1976, computer-generated proofs have become a reality in mathematics and computer science. During the last decade, we have seen formal proofs using verified proof assistants being used to verify the validity of such proofs.

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"
    - "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"
    - "formalization of abstract state transition systems for sat"
    - "co c e spheres and cells in computable metric spaces"

Connected through hyperedge HE-2 (induced by source paper "optimizing a certified proof checker for a large scale computer generated proof"):
  with members:
    - "twenty five comparators is optimal when sorting nine inputs and twenty nine for ten"
    - "the certification problem format"
    - "efficient generation of correctness certificates for the abstract domain of polyhedra"
    - "computer certified efficient exact reals in coq"
    - "certified exact transcendental real number computation in coq"

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)