human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "reduction monads and their signatures"):
  Abstract: In this work, we study reduction monads, which are essentially the same as monads relative to the free functor from sets into graphs. Reduction monads abstract two aspects of the lambda calculus: on the one hand, in the monadic viewpoint, it is an object equipped with a well-behaved substitution; on the other hand, in the graphical viewpoint, it is an oriented graph whose vertices are terms and whose edges witness the reductions between two terms.

Includes members:
  Member "modular specification of monads through higher order presentations":
    also connected through other hyperedges:
      (none)
  Member "signatures and models for syntax and operational semantics in the presence of variable binding":
    also connected through other hyperedges:
      (none)
  Member "high level signatures and initial semantics":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "signatures and models for syntax and operational semantics in the presence of variable binding")
  Member "lecture notes on the lambda calculus":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "signatures and models for syntax and operational semantics in the presence of variable binding")
  Member "modules over relative monads for syntax and semantics":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "modular specification of monads through higher order presentations")
  Member "monads need not be endofunctors":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "a type and scope safe universe of syntaxes with binding their semantics and proofs")
  Member "cartesian closed 2 categories and permutation equivalence in higher order rewriting":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "signatures and models for syntax and operational semantics in the presence of variable binding")
  Member "second order algebraic theories":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "a modular termination method for second order computation")

Question: Please tell me which class the source paper 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.PL(Programming Languages)