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: "syntactic complexity of r and j trivial regular languages"
  Abstract: The syntactic complexity of a subclass of the class of regular languages is the maximal cardinality of syntactic semigroups of languages in that class, taken as a function of the state complexity n of these languages. We prove that n! and ⌊e(n − 1)⌋. are tight upper bounds for the syntactic complexity of ℛ- and &#x1d4a5;-trivial regular languages, respectively.

Connected through hyperedge HE-1 (induced by source paper "completely reachable automata"):
  with members:
    - "reset complexity of ideal languages"
    - "primitive digraphs with large exponents and slowly synchronizing automata"
    - "the road coloring problem"

Connected through hyperedge HE-2 (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"
    - "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"
    - "quotient complexity of ideal languages"

Connected through hyperedge HE-3 (induced by source paper "on varieties of automata enriched with an algebraic structure extended abstract"):
  with members:
    - "separating regular languages with first order logic"
    - "on logical hierarchies withinfoâ definable languages"
    - "an introduction to finite automata and their connection to logic"
    - "algebraic recognizability of languages"

Connected through hyperedge HE-4 (induced by source paper "on the state complexity of the reverse of r and j trivial regular languages"):
  with members:
    - "efficient separability of regular languages by subsequences and suffixes"
    - "piecewise testable tree languages"
    - "regular ideal languages and their boolean combinations"

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)