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 non complete sets and restivo s conjecture"
  Abstract: A finite set S of words over the alphabet A is called non-complete if Fact(S*) is different from A*. A word w in A* - Fact(S*) is said to be uncompletable. We present a series of non-complete sets S_k whose minimal uncompletable words have length 5k^2 - 17k + 13, where k > 3 is the maximal length of words in S_k. This is an infinite series of counterexamples to Restivo's conjecture, which states that any non-complete set possesses an uncompletable word of length at most 2k^2.

Connected through hyperedge HE-1 (induced by source paper "the frobenius and factor universality problems of the free monoid on a finite set of words"):
  with members:
    - "on incomplete and synchronizing finite sets"
    - "an np hardness result on the monoid frobenius problem"
    - "the frobenius problem in a free monoid"

Connected through hyperedge HE-2 (induced by source paper "on nonnegative integer matrices and short killing words"):
  with members:
    - "finding short synchronizing words for prefix codes"
    - "efficient algorithms for deciding the type of growth of products of integer matrices"

Connected through hyperedge HE-3 (induced by source paper "on incomplete and synchronizing finite sets"):
  with members:
    - "independent sets of words and the synchronization problem"
    - "on the minimal uncompletable word problem"
    - "slowly synchronizing automata and digraphs"
    - "the road coloring problem"

Connected through hyperedge HE-4 (induced by source paper "the computational complexity of universality problems for prefixes suffixes factors and subwords of regular languages"):
  with members:
    - "on nfas where all states are final initial or both"
    - "the frobenius problem in a free monoid"

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)