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: "on the complexity of the model checking problem"
  Abstract: The model checking problem for various fragments of first-order logic has attracted much attention over the last two decades: in particular, for the primitive positive and the positive Horn fragments, which are better known as the constraint satisfaction problem and the quantified constraint satisfaction problem, respectively. These two fragments are in fact the only ones for which there is currently no known complexity classification. All other syntactic fragments can be easily classified, either directly or using Schaefer's dichotomy theorems for SAT and QSAT, with the exception of the positive equality free fragment. This outstanding fragment can also be classified and enjoys a tetrachotomy: according to the model, the corresponding model checking problem is either tractable, NP-complete, co-NP-complete or Pspace-complete. Moreover, the complexity drop is always witnessed by a generic solving algorithm which uses quantifier relativisation. Furthermore, its complexity is characterised by algebraic means: the presence or absence of specific surjective hyper-operations among those that preserve the model characterise the complexity.

Connected through hyperedge HE-1 (induced by source paper "qcsp monsters and the demise of the chen conjecture"):
  with members:
    - "a dichotomy theorem for nonuniform csps"
    - "the proof of csp dichotomy conjecture"
    - "the complexity of quantified constraints using the algebraic formulation"
    - "the algebraic dichotomy conjecture for infinite domain constraint satisfaction problems"
    - "quantified constraints and containment problems"
    - "the complexity of general valued csps"
    - "from complexity to algebra and back digraph classes collapsibility and the pgp"
    - "meditations on quantified constraint satisfaction"

Connected through hyperedge HE-2 (induced by source paper "the complexity of quantified constraints using the algebraic formulation"):
  with members:
    - "on the chen conjecture regarding the complexity of qcsps"

Connected through hyperedge HE-3 (induced by source paper "from complexity to algebra and back digraph classes collapsibility and the pgp"):
  with members:
    - "quantified constraints and containment problems"
    - "meditations on quantified constraint satisfaction"
    - "containment equivalence and coreness from csp to qcsp and beyond"
    - "qcsp on partially reflexive forests"
    - "the complexity of positive first order logic without equality"
    - "the complexity of quantified constraint satisfaction collapsibility sink algebras and the three element case"

Connected through hyperedge HE-4 (induced by source paper "switchability and collapsibility of gap algebras"):
  with members:
    - "from complexity to algebra and back digraph classes collapsibility and the pgp"

Connected through hyperedge HE-5 (induced by source paper "on the complexity of existential positive queries"):
  with members:
    - "tree width for first order formulae"
    - "tractable hypergraph properties for constraint satisfaction and conjunctive queries"
    - "the succinctness of first order logic on linear orders"

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.LO(Logic in Computer Science)