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: "tightening the complexity of equivalence problems for commutative grammars"
  Abstract: We show that the language equivalence problem for regular and context-free commutative grammars is coNEXP-complete. In addition, our lower bound immediately yields further coNEXP-completeness results for equivalence problems for communication-free Petri nets and reversal-bounded counter automata. Moreover, we improve both lower and upper bounds for language equivalence for exponent-sensitive commutative grammars.

Connected through hyperedge HE-1 (induced by source paper "containment of shape expression schemas for rdf"):
  with members:
    - "relational to rdf data exchange in presence of a shape expression schema"
    - "schemas for unordered xml on a dime"

Connected through hyperedge HE-2 (induced by source paper "context free commutative grammars with integer counters and resets"):
  with members:
    - "approaching the coverability problem continuously"
    - "complexity of problems of commutative grammars"
    - "demystifying reachability in vector addition systems"
    - "unary pushdown automata and straight line programs"
    - "integer vector addition systems with states"
    - "subclasses of presburger arithmetic and the weak exp hierarchy"
    - "semilinearity and context freeness of languages accepted by valence automata"

Connected through hyperedge HE-3 (induced by source paper "decidability and complexity for quiescent consistency and its variations"):
  with members:
    - "on verifying causal consistency"
    - "sequential consistency and concurrent data structures"
    - "on reducing linearizability to state reachability"
    - "between linearizability and quiescent consistency quantitative quiescent consistency"
    - "on the complexity of linearizability"

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)