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: "automatic theorem proving in walnut"
  Abstract: Walnut is a software package that implements a mechanical decision procedure for deciding certain combinatorial properties of some special words referred to as automatic words or automatic sequences. Walnut is written in Java and is open source. It is licensed under GNU General Public License.

Connected through hyperedge HE-1 (induced by source paper "new results on pseudosquare avoidance"):
  with members:
    - "anti powers in infinite words"
    - "fewest repetitions in infinite binary words"

Connected through hyperedge HE-2 (induced by source paper "circularly squarefree words and unbordered conjugates a new approach"):
  with members:
    - "circular critical exponents for thue morse factors"
    - "on ternary square free circular words"

Connected through hyperedge HE-3 (induced by source paper "computing the k binomial complexity of the thue morse word"):
  with members:
    - "relations on words"
    - "on the index of simon s congruence for piecewise testability"
    - "testing k binomial equivalence"
    - "avoiding 2 binomial squares and cubes"

Connected through hyperedge HE-4 (induced by source paper "automaticity and invariant measures of linear cellular automata"):
  with members:
    - "automatic sequences based on parry or bertrand numeration systems"
    - "enumeration and decidable properties of automatic sequences"

Connected through hyperedge HE-5 (induced by source paper "circular critical exponents for thue morse factors"):
  with members:
    - "repetition avoidance in circular factors"

Connected through hyperedge HE-6 (induced by source paper "deciding game invariance"):
  with members:
    - "mechanical proofs of properties of the tribonacci word"
    - "decision algorithms for fibonacci automatic words with applications to pattern avoidance"
    - "from heaps of matches to the limits of computability"

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)