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 "from algebra to logic there and back again the story of a hierarchy"):
  Abstract: This is an extended survey of the results concerning a hierarchy of languages that is tightly connected with the quantifier alternation hierarchy within the two-variable fragment of first order logic of the linear order.

Includes members:
  Member "essential convexity and complexity of semi algebraic constraints":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "a survey of challenges for runtime verification from advanced application domains beyond software")
  Member "an effective characterization of the alternation hierarchy in two variable logic":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "wreath products of distributive forest algebras")
  Member "the fo2 alternation hierarchy is decidable":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "the word problem for omega terms over the trotter weil hierarchy")
  Member "representations of stream processors using nested fixed points":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "infinite types infinite data infinite interaction")
  Member "structure theorem and strict alternation hierarchy for fo2 on words":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "two variable logics with some betweenness relations expressiveness satisfiability and membership")

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.FL(Formal Languages and Automata Theory)