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: "state complexity approximation"
  Abstract: In this paper, we introduce the new concept of state complexity approximation, which is a further development of state complexity estimation. We show that this new concept is useful in both of the following two cases: the exact state complexities are not known and the state complexities have been obtained but are in incomprehensible form.

Connected through hyperedge HE-1 (induced by source paper "a survey on operational state complexity"):
  with members:
    - "maximally atomic languages"
    - "upper bounds on syntactic complexity of left and two sided ideals"
    - "syntactic complexity of r and j trivial regular languages"
    - "most complex regular right ideal languages"
    - "the state complexity of star complement star"
    - "quotient complexity of star free languages"
    - "the magic number problem for subregular language families"
    - "nondeterministic state complexity for suffix free regular languages"

Connected through hyperedge HE-2 (induced by source paper "state complexity of two combined operations reversal catenation and star catenation"):
  with members:
    - "state complexity of catenation combined with star and reversal"
    - "state complexity of union and intersection combined with star and reversal"
    - "state complexity of orthogonal catenation"

Connected through hyperedge HE-3 (induced by source paper "state complexity of union and intersection combined with star and reversal"):
  with members:
    - "state complexity of catenation combined with star and reversal"
    - "state complexity of orthogonal catenation"

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.FL(Formal Languages and Automata Theory)