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: "defining functions on equivalence classes"
  Abstract: A quotient construction defines an abstract type from a concrete type, using an equivalence relation to identify elements of the concrete type that are to be regarded as indistinguishable. The elements of a quotient type are equivalence classes: sets of equivalent concrete values. Simple techniques are presented for defining and reasoning about quotient constructions, based on a general lemma library concerning functions that operate on equivalence classes. The techniques are applied to a definition of the integers from the natural numbers, and then to the definition of a recursive datatype satisfying equational constraints.

Connected through hyperedge HE-1 (induced by source paper "qed at large a survey of engineering of formally verified software"):
  with members:
    - "bridging the gap between programming languages and hardware weak memory models"
    - "automatic software repair a bibliography"
    - "the redprl proof assistant invited paper"
    - "verifying strong eventual consistency in distributed systems"
    - "algebraic foundations of proof refinement"
    - "deep network guided proof search"
    - "understanding and maintaining tactics graphically or how we are learning that a diagram can be worth more than 10k loc"
    - "gradual certified programming in coq"

Connected through hyperedge HE-2 (induced by source paper "a formalisation of finite automata using hereditarily finite sets"):
  with members:
    - "deciding kleene algebras in coq"
    - "essential convexity and complexity of semi algebraic constraints"

Connected through hyperedge HE-3 (induced by source paper "set theory or higher order logic to represent auction concepts in isabelle"):
  with members:
    - "proving soundness of combinatorial vickrey auctions and generating verified executable code"
    - "the formare project formal mathematical reasoning in economics"
    - "a qualitative comparison of the suitability of four theorem provers for basic auction theory"
    - "set theory for verification i from foundations to functions"

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)