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: "a new technique for reachability of states in concatenation automata"
  Abstract: We present a new technique for demonstrating the reachability of states in deterministic finite automata representing the concatenation of two languages. Such demonstrations are a necessary step in establishing the state complexity of the concatenation of two languages, and thus in establishing the state complexity of concatenation as an operation. Typically, ad-hoc induction arguments are used to show particular states are reachable in concatenation automata. We prove some results that seem to capture the essence of many of these induction arguments. Using these results, reachability proofs in concatenation automata can often be done more simply and without using induction directly.

Connected through hyperedge HE-1 (induced by source paper "most complex non returning regular languages"):
  with members:
    - "unrestricted state complexity of binary operations on regular languages"
    - "on the state complexity of the shuffle of regular languages"
    - "unrestricted state complexity of binary operations on regular and ideal languages"
    - "quotient complexities of atoms in regular ideal languages"
    - "complexity of suffix free regular languages"
    - "syntactic complexity of regular ideals"
    - "complexity of atoms combinatorially"
    - "symmetric groups and quotient complexity of boolean operations"

Connected through hyperedge HE-2 (induced by source paper "most complex deterministic union free regular languages"):
  with members:
    - "unrestricted state complexity of binary operations on regular and ideal languages"
    - "quotient complexities of atoms in regular ideal languages"
    - "most complex regular ideal languages"
    - "complexity of atoms combinatorially"
    - "symmetric groups and quotient complexity of boolean operations"
    - "large aperiodic semigroups"
    - "theory of atomata"

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)