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: "tactics for reasoning modulo ac in coq"
  Abstract: We present a set of tools for rewriting modulo associativity and commutativity (AC) in Coq, solving a long-standing practical problem. We use two building blocks: first, an extensible reflexive decision procedure for equality modulo AC; second, an OCaml plug-in for pattern matching modulo AC. We handle associative only operations, neutral elements, uninterpreted function symbols, and user-defined equivalence relations. By relying on type-classes for the reification phase, we can infer these properties automatically, so that end-users do not need to specify which operation is A or AC, or which constant is a neutral element.

Connected through hyperedge HE-1 (induced by source paper "incorporating quotation and evaluation into church s type theory"):
  with members:
    - "hol light qe"
    - "theory morphisms in church s type theory with quotation and evaluation"
    - "formalizing mathematical knowledge as a biform theory graph a case study"
    - "modelling homogeneous generative meta programming"
    - "incorporating quotation and evaluation into church s type theory syntax and semantics"
    - "on the semantics of reflect as a basis for a reflective theorem prover"
    - "the formalization of syntax based mathematical algorithms using quotation and evaluation"
    - "frameworks for reasoning about syntax that utilize quotation and evaluation"

Connected through hyperedge HE-2 (induced by source paper "hol light qe"):
  with members:
    - "incorporating quotation and evaluation into church s type theory"
    - "on the semantics of intensionality and intensional recursion"
    - "formalizing mathematical knowledge as a biform theory graph a case study"
    - "incorporating quotation and evaluation into church s type theory syntax and semantics"
    - "on the semantics of reflect as a basis for a reflective theorem prover"
    - "the formalization of syntax based mathematical algorithms using quotation and evaluation"

Connected through hyperedge HE-3 (induced by source paper "nominal c unification"):
  with members:
    - "nominal unification of higher order expressions with recursive let"
    - "closed nominal rewriting and efficiently computable nominal algebra equality"
    - "nominal unification revisited"

Connected through hyperedge HE-4 (induced by source paper "mirrorshard proof by computational reflection with verified hints"):
  with members:
    - "type classes for mathematics in type theory"

Connected through hyperedge HE-5 (induced by source paper "barriers in concurrent separation logic now with tool support"):
  with members:
    - "separation logic for small step cminor"

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.MS(Mathematical Software)