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: "the drat format and drat trim checker"
  Abstract: This document describes the DRAT format for clausal proofs and the DRAT-trim proof checker.

Connected through hyperedge HE-1 (induced by source paper "efficient certified resolution proof checking"):
  with members:
    - "efficient certified rat verification"
    - "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"
    - "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 "efficient certified rat verification"):
  with members:
    - "efficient certified resolution proof checking"
    - "solving and verifying the boolean pythagorean triples problem via cube and conquer"
    - "formalization of abstract state transition systems for sat"

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)