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 the fundamental group in untyped set theory using auto2"
  Abstract: We present a new framework for formalizing mathematics in untyped set theory using auto2. Using this framework, we formalize in Isabelle/FOL the entire chain of development from the axioms of set theory to the definition of the fundamental group for an arbitrary topological space. The auto2 prover is used as the sole automation tool, and enables succinct proof scripts throughout the project.

Connected through hyperedge HE-1 (induced by source paper "formalising mathematics in simple type theory"):
  with members:
    - "computational logic its origins and applications"
    - "natural deduction as higher order resolution"
    - "constructing recursion operators in intuitionistic type theory"
    - "mechanizing coinduction and corecursion in higher order logic"

Connected through hyperedge HE-2 (induced by source paper "computational logic its origins and applications"):
  with members:
    - "a formally verified proof of the central limit theorem"
    - "natural deduction as higher order resolution"
    - "the foundation of a generic theorem prover"
    - "inductive analysis of the internet protocol tls"
    - "isabelle the next 700 theorem provers"

Connected through hyperedge HE-3 (induced by source paper "first steps towards a formalization of forcing"):
  with members:
    - "set theory for verification ii induction and recursion"

Connected through hyperedge HE-4 (induced by source paper "efficient verification of imperative programs using auto2"):
  with members:
    - "auto2 a saturation based heuristic prover for higher order logic"

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)