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: "concurrent kleene algebra free model and completeness"
  Abstract: Concurrent Kleene Algebra (CKA) was introduced by Hoare, Moeller, Struth and Wehrman in 2009 as a framework to reason about concurrent programs. We prove that the axioms for CKA with bounded parallelism are complete for the semantics proposed in the original paper; consequently, these semantics are the free model for this fragment. This result settles a conjecture of Hoare and collaborators. Moreover, the techniques developed along the way are reusable; in particular, they allow us to establish pomset automata as an operational model for CKA.

Connected through hyperedge HE-1 (induced by source paper "concurrent kleene algebra with observations from hypotheses to completeness"):
  with members:
    - "kleene algebra with observations"
    - "completeness and incompleteness of synchronous kleene algebra"

Connected through hyperedge HE-2 (induced by source paper "completeness and incompleteness of synchronous kleene algebra"):
  with members:
    - "kleene algebra with observations"
    - "completeness theorems for pomset languages and concurrent kleene algebras"
    - "a synchronous program algebra a basis for reasoning about shared memory and event based concurrency"
    - "an algebra of synchronous atomic steps"
    - "generalised rely guarantee concurrency an algebraic foundation"

Connected through hyperedge HE-3 (induced by source paper "generating posets beyond n"):
  with members:
    - "kleene algebra with observations"
    - "completeness theorems for pomset languages and concurrent kleene algebras"
    - "presenting finite posets"
    - "concurrent dynamic algebra"

Connected through hyperedge HE-4 (induced by source paper "on series parallel pomset languages rationality context freeness and automata"):
  with members:
    - "completeness theorems for pomset languages and concurrent kleene algebras"
    - "brzozowski goes concurrent a kleene theorem for pomset languages"

Connected through hyperedge HE-5 (induced by source paper "a note on commutative kleene algebra"):
  with members:
    - "concurrent kleene algebra with observations from hypotheses to completeness"

Connected through hyperedge HE-6 (induced by source paper "equivalence checking for weak bi kleene algebra"):
  with members:
    - "on series parallel pomset languages rationality context freeness and automata"
    - "brzozowski goes concurrent a kleene theorem for pomset languages"

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)