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: "a characterisation of first order constraint satisfaction problems"
  Abstract: We describe simple algebraic and combinatorial characterisations of finite#N#relational core structures admitting finitely many obstructions. As a#N#consequence, we show that it is decidable to determine whether a constraint#N#satisfaction problem is first-order definable: we show the general problem to#N#be NP-complete, and give a polynomial-time algorithm in the case of cores. A#N#slight modification of this algorithm provides, for first-order definable#N#CSP's, a simple poly-time algorithm to produce a solution when one exists. As#N#an application of our algebraic characterisation of first order CSP's, we#N#describe a large family of L-complete CSP's.

Connected through hyperedge HE-1 (induced by source paper "rewritability in monadic disjunctive datalog mmsnp and expressive description logics"):
  with members:
    - "a dichotomy theorem for nonuniform csps"
    - "the proof of csp dichotomy conjecture"
    - "the data complexity of description logic ontologies"
    - "asking the metaquestions in constraint tractability"
    - "ontology based data access a study through disjunctive datalog csp and mmsnp"
    - "universal structures and the logic of forbidden patterns"
    - "the dl lite family and relations"
    - "datalog and constraint satisfaction with infinite templates"

Connected through hyperedge HE-2 (induced by source paper "a dichotomy theorem for nonuniform csps"):
  with members:
    - "constraint satisfaction problems over semilattice block mal tsev algebras"
    - "weaker consistency notions for all the csps of bounded width"
    - "asking the metaquestions in constraint tractability"
    - "graphs of finite algebras edges and connectivity"
    - "conservative constraint satisfaction re revisited"
    - "absorbing subalgebras cyclic terms and the constraint satisfaction problem"

Connected through hyperedge HE-3 (induced by source paper "surjective h colouring over reflexive digraphs"):
  with members:
    - "surjective h colouring new hardness results"
    - "a dichotomy theorem for nonuniform csps"
    - "the proof of csp dichotomy conjecture"
    - "an algebraic hardness criterion for surjective constraint satisfaction"
    - "the complexity of surjective homomorphism problems a survey"

Connected through hyperedge HE-4 (induced by source paper "the data complexity of description logic ontologies"):
  with members:
    - "a dichotomy theorem for nonuniform csps"
    - "the proof of csp dichotomy conjecture"
    - "rewritability in monadic disjunctive datalog mmsnp and expressive description logics"
    - "querying the guarded fragment"
    - "ontology based data access a study through disjunctive datalog csp and mmsnp"
    - "description logic tboxes model theoretic characterizations and rewritability"
    - "the dl lite family and relations"
    - "conjunctive query answering for the description logic shiq"

Connected through hyperedge HE-5 (induced by source paper "a finer reduction of constraint problems to digraphs"):
  with members:
    - "the complexity of general valued csps"
    - "an algebraic theory of complexity for discrete optimization"
    - "on the reduction of the csp dichotomy conjecture to digraphs"
    - "absorbing subalgebras cyclic terms and the constraint satisfaction problem"
    - "on the scope of the universal algebraic approach to constraint satisfaction"
    - "the dichotomy of list homomorphisms for digraphs"

Connected through hyperedge HE-6 (induced by source paper "ontology based data access a study through disjunctive datalog csp and mmsnp"):
  with members:
    - "querying the guarded fragment"
    - "computing datalog rewritings beyond horn ontologies"
    - "exponential lower bounds and separation for query rewriting"
    - "type elimination based reasoning for the description logic shiqbs using decision diagrams and disjunctive datalog"
    - "rewriting ontological queries into small nonrecursive datalog programs"
    - "universal structures and the logic of forbidden patterns"

Connected through hyperedge HE-7 (induced by source paper "space complexity of list h colouring a dichotomy"):
  with members:
    - "on the reduction of the csp dichotomy conjecture to digraphs"
    - "the dichotomy of list homomorphisms for digraphs"
    - "the complexity of the list homomorphism problem for graphs"

Connected through hyperedge HE-8 (induced by source paper "complexity classification in infinite domain constraint satisfaction"):
  with members:
    - "absorbing subalgebras cyclic terms and the constraint satisfaction problem"
    - "on the scope of the universal algebraic approach to constraint satisfaction"
    - "tractable set constraints"
    - "datalog and constraint satisfaction with infinite templates"
    - "a fast algorithm and datalog inexpressibility for temporal reasoning"
    - "cores of countably categorical structures"
    - "linear datalog and bounded path duality of relational structures"
    - "a complete classification of tractability in rcc 5"

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)