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: "separating regular languages with first order logic"
  Abstract: Given two languages, a separator is a third language that contains the first#N#one and is disjoint from the second one. We investigate the following decision#N#problem: given two regular input languages of finite words, decide whether#N#there exists a first-order definable separator. We prove that in order to#N#answer this question, sufficient information can be extracted from semigroups#N#recognizing the input languages, using a fixpoint computation. This yields an#N#EXPTIME algorithm for checking first-order separability. Moreover, the#N#correctness proof of this algorithm yields a stronger result, namely a#N#description of a possible separator. Finally, we generalize this technique to#N#answer the same question for regular languages of infinite words.

Connected through hyperedge HE-1 (induced by source paper "regular separability and intersection emptiness are independent problems"):
  with members:
    - "separation for dot depth two"
    - "the covering problem"
    - "regular separability of one counter automata"
    - "regular separability of parikh automata"
    - "separability of reachability sets of vector addition systems"
    - "unboundedness and downward closures of higher order pushdown automata"
    - "an approach to computing downward closures"
    - "a characterization for decidable separability by piecewise testable languages"

Connected through hyperedge HE-2 (induced by source paper "on all things star free"):
  with members:
    - "separation and covering for group based concatenation hierarchies"
    - "separation for dot depth two"
    - "the covering problem"
    - "generic results for concatenation hierarchies"
    - "characterizing classes of regular languages using prefix codes of bounded synchronization delay"
    - "going higher in the first order quantifier alternation hierarchy on words"

Connected through hyperedge HE-3 (induced by source paper "separation for dot depth two"):
  with members:
    - "the covering problem"
    - "generic results for concatenation hierarchies"
    - "going higher in the first order quantifier alternation hierarchy on words"
    - "separating regular languages by piecewise testable and unambiguous languages"
    - "efficient separability of regular languages by subsequences and suffixes"

Connected through hyperedge HE-4 (induced by source paper "covering and separation for logical fragments with modular predicates"):
  with members:
    - "separation for dot depth two"
    - "the covering problem"
    - "adding successor a transfer theorem for separation and covering"
    - "adding modular predicates to first order fragments"
    - "going higher in the first order quantifier alternation hierarchy on words"
    - "one quantifier alternation in first order logic with modular predicates"
    - "separating regular languages by piecewise testable and unambiguous languages"
    - "efficient separability of regular languages by subsequences and suffixes"

Connected through hyperedge HE-5 (induced by source paper "regular separability of one counter automata"):
  with members:
    - "regular separability of well structured transition systems"
    - "regular separability of parikh automata"
    - "separability of reachability sets of vector addition systems"
    - "invisible pushdown languages"
    - "reachability in two dimensional vector addition systems with states is pspace complete"
    - "going higher in the first order quantifier alternation hierarchy on words"
    - "reachability in two clock timed automata is pspace complete"
    - "separating regular languages by piecewise testable and unambiguous languages"

Connected through hyperedge HE-6 (induced by source paper "adding successor a transfer theorem for separation and covering"):
  with members:
    - "the covering problem"
    - "separating regular languages with two quantifier alternations"
    - "going higher in first order quantifier alternation hierarchies on words"
    - "quantifier alternation for infinite words"
    - "going higher in the first order quantifier alternation hierarchy on words"
    - "separating regular languages by piecewise testable and unambiguous languages"
    - "efficient separability of regular languages by subsequences and suffixes"
    - "around dot depth one"

Connected through hyperedge HE-7 (induced by source paper "going higher in first order quantifier alternation hierarchies on words"):
  with members:
    - "separating regular languages with two quantifier alternations"
    - "on the index of simon s congruence for piecewise testability"
    - "going higher in the first order quantifier alternation hierarchy on words"
    - "separating regular languages by piecewise testable and unambiguous languages"
    - "efficient separability of regular languages by subsequences and suffixes"

Connected through hyperedge HE-8 (induced by source paper "quantifier alternation for infinite words"):
  with members:
    - "separating regular languages with two quantifier alternations"
    - "level two of the quantifier alternation hierarchy over infinite words"
    - "going higher in the first order quantifier alternation hierarchy on words"
    - "separating regular languages by piecewise testable and unambiguous languages"
    - "efficient separability of regular languages by subsequences and suffixes"
    - "fragments of first order logic over infinite words"

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)