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: "on the state complexity of closures and interiors of regular languages with subwords and superwords"
  Abstract: The downward and upward closures of a regular language L are obtained by collecting all the subwords and superwords of its elements, respectively. The downward and upward interiors of L are obtained dually by collecting words having all their subwords and superwords in L, respectively. We provide lower and upper bounds on the size of the smallest automata recognizing these closures and interiors. We also consider the computational complexity of decision problems for closures of regular languages.

Connected through hyperedge HE-1 (induced by source paper "well quasiorders and hierarchy theory"):
  with members:
    - "decidability in the logic of subsequences and supersequences"
    - "generalized post embedding problems"
    - "the height of piecewise testable languages with applications in logical complexity"
    - "fragments of first order logic over infinite words"

Connected through hyperedge HE-2 (induced by source paper "decidability complexity and expressiveness of first order logic over the subword ordering"):
  with members:
    - "decidability in the logic of subsequences and supersequences"
    - "generalized post embedding problems"
    - "the height of piecewise testable languages with applications in logical complexity"
    - "subclasses of presburger arithmetic and the weak exp hierarchy"
    - "the power of priority channel systems"
    - "recompression a simple and powerful technique for word equations"

Connected through hyperedge HE-3 (induced by source paper "the height of piecewise testable languages and the complexity of the logic of subwords"):
  with members:
    - "piecewise testable languages and nondeterministic automata"
    - "decidability in the logic of subsequences and supersequences"
    - "on the index of simon s congruence for piecewise testability"
    - "an approach to computing downward closures"
    - "the height of piecewise testable languages with applications in logical complexity"
    - "finite automata for the sub and superword closure of cfls descriptional and computational complexity"
    - "recompression a simple and powerful technique for word equations"
    - "piecewise testable tree languages"

Connected through hyperedge HE-4 (induced by source paper "a note on decidable separability by piecewise testable languages"):
  with members:
    - "demystifying reachability in vector addition systems"
    - "an approach to computing downward closures"
    - "computing downward closures for stacked counter automata"
    - "the power of well structured systems"
    - "the separation problem for regular languages by piecewise testable languages"
    - "separating regular languages by piecewise testable and unambiguous languages"
    - "piecewise testable tree languages"
    - "model checking vector addition systems with one zero test"

Connected through hyperedge HE-5 (induced by source paper "alternating towers and piecewise testable separators"):
  with members:
    - "separating regular languages with first order logic"
    - "on upper and lower bounds on the length of alternating towers"
    - "going higher in the first order quantifier alternation hierarchy on words"
    - "separating regular languages by piecewise testable and unambiguous languages"
    - "efficient separability of regular languages by subsequences and suffixes"

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)