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: "ontology based data access a study through disjunctive datalog csp and mmsnp"
  Abstract: Ontology-based data access is concerned with querying incomplete data sources in the presence of domain-specific knowledge provided by an ontology. A central notion in this setting is that of an ontology-mediated query, which is a database query coupled with an ontology. In this paper, we study several classes of ontology-mediated queries, where the database queries are given as some form of conjunctive query and the ontologies are formulated in description logics or other relevant fragments of first-order logic, such as the guarded fragment and the unary-negation fragment. The contributions of the paper are three-fold. First, we characterize the expressive power of ontology-mediated queries in terms of fragments of disjunctive datalog. Second, we establish intimate connections between ontology-mediated queries and constraint satisfaction problems (CSPs) and their logical generalization, MMSNP formulas. Third, we exploit these connections to obtain new results regarding (i) first-order rewritability and datalog-rewritability of ontology-mediated queries, (ii) P/NP dichotomies for ontology-mediated queries, and (iii) the query containment problem for ontology-mediated queries.

Connected through hyperedge HE-1 (induced by source paper "asnp a tame fragment of existential second order logic"):
  with members:
    - "a universal algebraic proof of the complexity dichotomy for monotone monadic snp"
    - "a dichotomy theorem for nonuniform csps"
    - "the algebraic dichotomy conjecture for infinite domain constraint satisfaction problems"
    - "complexity classification in infinite domain constraint satisfaction"
    - "universal structures and the logic of forbidden patterns"
    - "datalog and constraint satisfaction with infinite templates"

Connected through hyperedge HE-2 (induced by source paper "when is ontology mediated querying efficient"):
  with members:
    - "the complexity of ontology based data access with owl 2 ql and bounded treewidth queries"
    - "semantic acyclicity under constraints"
    - "ontology mediated queries combined complexity and succinctness of rewritings via circuit complexity"
    - "on the complexity of existential positive queries"
    - "the dl lite family and relations"

Connected through hyperedge HE-3 (induced by source paper "polynomial rewritings from expressive description logics with closed predicates to variants of datalog"):
  with members:
    - "nested regular path queries in description logics"
    - "rewriting ontological queries into small nonrecursive datalog programs"

Connected through hyperedge HE-4 (induced by source paper "a journey into ontology approximation from non horn to hon"):
  with members:
    - "rewritability in monadic disjunctive datalog mmsnp and expressive description logics"

Connected through hyperedge HE-5 (induced by source paper "query inseparability for alc ontologies"):
  with members:
    - "conservative extensions in guarded and two variable fragments"
    - "inseparability and conservative extensions of description logic ontologies a survey"
    - "optimizing sparql query answering over owl ontologies"
    - "acyclicity notions for existential rules and their application to query answering in ontologies"
    - "exchanging owl 2 ql knowledge bases"
    - "the logical difference for the lightweight description logic el"
    - "foundations for uniform interpolation and forgetting in expressive description logics"
    - "semantical characterizations and complexity of equivalences in answer set programming"

Connected through hyperedge HE-6 (induced by source paper "the limits of efficiency for open and closed world query evaluation under guarded tgds"):
  with members:
    - "when is ontology mediated querying efficient"
    - "containment for rule based ontology mediated queries"
    - "semantic acyclicity under constraints"
    - "querying the guarded fragment"
    - "guarded second order logic spanning trees and network flows"
    - "tractable hypergraph properties for constraint satisfaction and conjunctive queries"

Connected through hyperedge HE-7 (induced by source paper "a dichotomy for homomorphism closed queries on probabilistic graphs"):
  with members:
    - "boundedness of conjunctive regular path queries"
    - "model counting for conjunctive queries without self joins"
    - "tractable lineages on treelike instances limits and extensions"
    - "rewriting ontological queries into small nonrecursive datalog programs"

Connected through hyperedge HE-8 (induced by source paper "data complexity and rewritability of ontology mediated queries in metric temporal logic under the event based semantics full version"):
  with members:
    - "querying log data with metric temporal logic"
    - "stream reasoning in temporal datalog"
    - "query rewriting and optimization for ontological databases"

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.DB(Databases)