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: "lower bounds for existential pebble games and k consistency tests"
  Abstract: The existential k-pebble game characterizes the expressive power of the#N#existential-positive k-variable fragment of first-order logic on finite#N#structures. The winner of the existential k-pebble game on two given finite#N#structures can be determined in time O(n2k) by dynamic programming on the graph#N#of game configurations. We show that there is no O(n(k-3)/12)-time algorithm#N#that decides which player can win the existential k-pebble game on two given#N#structures. This lower bound is unconditional and does not rely on any#N#complexity-theoretic assumptions. Establishing strong k-consistency is a#N#well-known heuristic for solving the constraint satisfaction problem (CSP). By#N#the game characterization of Kolaitis and Vardi our result implies that there#N#is no O(n(k-3)/12)-time algorithm that decides if strong k-consistency can be#N#established for a given CSP-instance.

Connected through hyperedge HE-1 (induced by source paper "constructing hard examples for graph isomorphism"):
  with members:
    - "definable inapproximability new challenges for duplicator"
    - "an exponential lower bound for individualization refinement algorithms for graph isomorphism"
    - "the pebbling comonad in finite model theory"
    - "benchmark graphs for practical graph isomorphism"
    - "graph isomorphism in quasipolynomial time"
    - "practical graph isomorphism ii"
    - "clause learning algorithms with many restarts and bounded width resolution"

Connected through hyperedge HE-2 (induced by source paper "the propagation depth of local consistency"):
  with members:
    - "on the speed of constraint propagation and the time complexity of arc consistency testing"

Connected through hyperedge HE-3 (induced by source paper "on the speed of constraint propagation and the time complexity of arc consistency testing"):
  with members:
    - "the propagation depth of local consistency"
    - "graph logics with rational relations"
    - "bounds for the quantifier depth in finite variable logics alternation hierarchy"
    - "on the complexity of finding narrow proofs"

Connected through hyperedge HE-4 (induced by source paper "on the dynamic width of the 3 colorability problem"):
  with members:
    - "on the speed of constraint propagation and the time complexity of arc consistency testing"
    - "planar graphs logical complexity and parallel isomorphism tests"
    - "3 coloring in time o 1 3289 n"

Connected through hyperedge HE-5 (induced by source paper "on the complexity of finding narrow proofs"):
  with members:
    - "pebble games proof complexity and time space trade offs"
    - "width and size of regular resolution proofs"
    - "clause learning algorithms with many restarts and bounded width resolution"
    - "towards an optimal separation of space and length in resolution"

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)