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: "acyclicity notions for existential rules and their application to query answering in ontologies"
  Abstract: Answering conjunctive queries (CQs) over a set of facts extended with existential rules is a prominent problem in knowledge representation and databases. This problem can be solved using the chase algorithm, which extends the given set of facts with fresh facts in order to satisfy the rules. If the chase terminates, then CQs can be evaluated directly in the resulting set of facts. The chase, however, does not terminate necessarily, and checking whether the chase terminates on a given set of rules and facts is undecidable. Numerous acyclicity notions were proposed as sufficient conditions for chase termination. In this paper, we present two new acyclicity notions called model-faithful acyclicity (MFA) and model-summarising acyclicity (MSA). Furthermore, we investigate the landscape of the known acyclicity notions and establish a complete taxonomy of all notions known to us. Finally, we show that MFA and MSA generalise most of these notions.#R##N##R##N#Existential rules are closely related to the Horn fragments of the OWL 2 ontology language; furthermore, several prominent OWL 2 reasoners implement CQ answering by using the chase to materialise all relevant facts. In order to avoid termination problems, many of these systems handle only the OWL 2 RL profile of OWL 2; furthermore, some systems go beyond OWL 2 RL, but without any termination guarantees. In this paper we also investigate whether various acyclicity notions can provide a principled and practical solution to these problems. On the theoretical side, we show that query answering for acyclic ontologies is of lower complexity than for general ontologies. On the practical side, we show that many of the commonly used OWL 2 ontologies are MSA, and that the number of facts obtained by materialisation is not too large. Our results thus suggest that principled development of materialisation-based OWL 2 reasoners is practically feasible.

Connected through hyperedge HE-1 (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"
    - "ontology based data access a study through disjunctive datalog csp and mmsnp"
    - "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-2 (induced by source paper "all instances restricted chase termination"):
  with members:
    - "a single approach to decide chase termination on linear existential rules"
    - "semantic acyclicity under constraints"
    - "anatomy of the chase"
    - "on chase termination beyond stratification"

Connected through hyperedge HE-3 (induced by source paper "checking chase termination over ontologies of existential rules with equality"):
  with members:
    - "a practical acyclicity notion for query answering over horn mathcal sriq ontologies"

Connected through hyperedge HE-4 (induced by source paper "a new finitely controllable class of tuple generating dependencies the triangularly guarded class"):
  with members:
    - "existential rule languages with finite chase complexity and expressiveness"
    - "converging to the chase a tool for finite controllability"

Connected through hyperedge HE-5 (induced by source paper "the complexity of ontology based data access with owl 2 ql and bounded treewidth queries"):
  with members:
    - "query rewriting and optimization for ontological databases"
    - "tree like queries in owl 2 ql succinctness and complexity results"
    - "sound complete and minimal ucq rewriting for existential rules"
    - "exponential lower bounds and separation for query rewriting"

Connected through hyperedge HE-6 (induced by source paper "a practical acyclicity notion for query answering over horn mathcal sriq ontologies"):
  with members:
    - "introducing nominals to the combined query answering approaches for el"
    - "nominals inverses counting and conjunctive queries or why infinity is your friend"
    - "conjunctive query answering for the description logic shiq"

Connected through hyperedge HE-7 (induced by source paper "combining existential rules and transitivity next steps"):
  with members:
    - "conjunctive query answering for the description logic shiq"

Connected through hyperedge HE-8 (induced by source paper "existential rule languages with finite chase complexity and expressiveness"):
  with members:
    - "disjunctive datalog with existential quantifiers semantics decidability and complexity issues"

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)