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: "quotient complexity of closed languages"
  Abstract: A language L is prefix-closed if, whenever a word w is in L, then every prefix of w is also in L. We define suffix-, factor-, and subword-closed languages in the same way, where by subword we mean subsequence. We study the quotient complexity (usually called state complexity) of operations on prefix-, suffix-, factor-, and subword-closed languages. We find tight upper bounds on the complexity of the prefix-, suffix-, factor-, and subword-closure of arbitrary languages, and on the complexity of boolean operations, concatenation, star and reversal in each of the four classes of closed languages. We show that repeated application of positive closure and complement to a closed language results in at most four distinct languages, while Kleene closure and complement gives at most eight languages.

Connected through hyperedge HE-1 (induced by source paper "towards a theory of complexity of regular languages"):
  with members:
    - "most complex non returning regular languages"
    - "unrestricted state complexity of binary operations on regular languages"
    - "unrestricted state complexity of binary operations on regular and ideal languages"
    - "most complex regular ideal languages"
    - "syntactic complexity of regular ideals"
    - "maximally atomic languages"
    - "upper bounds on syntactic complexity of left and two sided ideals"
    - "complexity of atoms combinatorially"

Connected through hyperedge HE-2 (induced by source paper "a new technique for reachability of states in concatenation automata"):
  with members:
    - "most complex non returning regular languages"
    - "unrestricted state complexity of binary operations on regular languages"
    - "most complex regular ideal languages"
    - "quotient complexity of star free languages"
    - "complexity in prefix free regular languages"
    - "quotient complexity of ideal languages"

Connected through hyperedge HE-3 (induced by source paper "complexity of left ideal suffix closed and suffix free regular languages"):
  with members:
    - "unrestricted state complexity of binary operations on regular languages"
    - "unrestricted state complexity of binary operations on regular and ideal languages"
    - "quotient complexities of atoms in regular ideal languages"
    - "most complex regular ideal languages"
    - "syntactic complexity of regular ideals"
    - "upper bounds on syntactic complexity of left and two sided ideals"
    - "complexity of atoms combinatorially"
    - "symmetric groups and quotient complexity of boolean operations"

Connected through hyperedge HE-4 (induced by source paper "complexity of prefix convex regular languages"):
  with members:
    - "unrestricted state complexity of binary operations on regular languages"
    - "quotient complexities of atoms in regular ideal languages"
    - "most complex regular ideal languages"
    - "syntactic complexity of regular ideals"
    - "maximally atomic languages"
    - "complexity of atoms combinatorially"
    - "symmetric groups and quotient complexity of boolean operations"
    - "quotient complexities of atoms of regular languages"

Connected through hyperedge HE-5 (induced by source paper "syntactic complexity of regular ideals"):
  with members:
    - "syntactic complexity of bifix free languages"
    - "upper bounds on syntactic complexity of left and two sided ideals"
    - "large aperiodic semigroups"
    - "syntactic complexity of prefix suffix bifix and factor free regular languages"
    - "theory of atomata"
    - "syntactic complexity of ideal and closed languages"
    - "quotient complexity of ideal languages"
    - "decision problems for convex languages"

Connected through hyperedge HE-6 (induced by source paper "operations on automata with all states final"):
  with members:
    - "quotient complexity of ideal languages"
    - "on nfas where all states are final initial or both"
    - "the state complexity of l 2 and l k"

Connected through hyperedge HE-7 (induced by source paper "syntactic complexity of ideal and closed languages"):
  with members:
    - "quotient complexity of ideal languages"
    - "decision problems for convex languages"
    - "quotient complexity of regular languages"
    - "on nfas where all states are final initial or both"

Connected through hyperedge HE-8 (induced by source paper "combinatorial characterization of formal languages"):
  with members:
    - "almost overlap free words and the word problem for the free burnside semigroup satisfying x 2 x 3"
    - "on ternary square free circular words"
    - "quotient complexity of regular languages"

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)