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 "on all things star free"):
  Abstract: We investigate the star-free closure, which associates to a class of languages its closure under Boolean operations and marked concatenation. We prove that the star-free closure of any finite class and of any class of groups languages with decidable separation (plus mild additional properties) has decidable separation. We actually show decidability of a stronger property, called covering. This generalizes many results on the subject in a unified framework. A key ingredient is that star-free closure coincides with another closure operator where Kleene stars are also allowed in restricted contexts.

Includes members:
  Member "separation and covering for group based concatenation hierarchies":
    also connected through other hyperedges:
      (none)
  Member "separation for dot depth two":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "regular separability and intersection emptiness are independent problems")
  Member "the covering problem":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "partially ordered automata and piecewise testability")
  Member "generic results for concatenation hierarchies":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "separation for dot depth two")
  Member "separating regular languages with first order logic":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "regular separability and intersection emptiness are independent problems")
  Member "characterizing classes of regular languages using prefix codes of bounded synchronization delay":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "church rosser systems codes with bounded synchronization delay and local rees extensions")
  Member "going higher in the first order quantifier alternation hierarchy on words":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "separation for dot depth two")

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)