When is Ontology-Mediated Querying Efficient?

• URL: http://arxiv.org/abs/2003.07800v2
• Date: Wed, 29 Jul 2020 15:25:57 GMT
• Title: When is Ontology-Mediated Querying Efficient?
• Authors: Pablo Barcelo, Cristina Feier, Carsten Lutz, Andreas Pieris
• Abstract summary: We study the evaluation of ontology-mediated queries over relational databases. We provide a characterization of the classes of OMQs that are tractable in combined complexity. We also study the complexity of deciding whether a given OMQ is equivalent to an OMQ of bounded tree width.
• Score: 10.971122842236024
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: In ontology-mediated querying, description logic (DL) ontologies are used to enrich incomplete data with domain knowledge which results in more complete answers to queries. However, the evaluation of ontology-mediated queries (OMQs) over relational databases is computationally hard. This raises the question when OMQ evaluation is efficient, in the sense of being tractable in combined complexity or fixed-parameter tractable. We study this question for a range of ontology-mediated query languages based on several important and widely-used DLs, using unions of conjunctive queries as the actual queries. For the DL ELHI extended with the bottom concept, we provide a characterization of the classes of OMQs that are fixed-parameter tractable. For its fragment EL extended with domain and range restrictions and the bottom concept (which restricts the use of inverse roles), we provide a characterization of the classes of OMQs that are tractable in combined complexity. Both results are in terms of equivalence to OMQs of bounded tree width and rest on a reasonable assumption from parameterized complexity theory. They are similar in spirit to Grohe's seminal characterization of the tractable classes of conjunctive queries over relational databases. We further study the complexity of the meta problem of deciding whether a given OMQ is equivalent to an OMQ of bounded tree width, providing several completeness results that range from NP to 2ExpTime, depending on the DL used. We also consider the DL-Lite family of DLs, including members that admit functional roles.

Related papers

• GRS-QA -- Graph Reasoning-Structured Question Answering Dataset [50.223851616680754]
  We introduce the Graph Reasoning-Structured Question Answering dataset (GRS-QA), which includes both semantic contexts and reasoning structures for QA pairs. Unlike existing M-QA datasets, GRS-QA explicitly captures intricate reasoning pathways by constructing reasoning graphs. Our empirical analysis reveals that LLMs perform differently when handling questions with varying reasoning structures.
  arXiv  Detail & Related papers  (2024-11-01T05:14:03Z)
• Adaptive-RAG: Learning to Adapt Retrieval-Augmented Large Language Models through Question Complexity [59.57065228857247]
  Retrieval-augmented Large Language Models (LLMs) have emerged as a promising approach to enhancing response accuracy in several tasks, such as Question-Answering (QA) We propose a novel adaptive QA framework, that can dynamically select the most suitable strategy for (retrieval-augmented) LLMs based on the query complexity. We validate our model on a set of open-domain QA datasets, covering multiple query complexities, and show that ours enhances the overall efficiency and accuracy of QA systems.
  arXiv  Detail & Related papers  (2024-03-21T13:52:30Z)
• Uni-Parser: Unified Semantic Parser for Question Answering on Knowledge Base and Database [86.03294330305097]
  We propose a unified semantic element for question answering (QA) on both knowledge bases (KB) and databases (DB) We introduce the primitive (relation and entity in KB, table name, column name and cell value in DB) as an essential element in our framework. We leverage the generator to predict final logical forms by altering and composing topranked primitives with different operations.
  arXiv  Detail & Related papers  (2022-11-09T19:33:27Z)
• Ontology-Mediated Querying on Databases of Bounded Cliquewidth [10.880181451789262]
  We study the evaluation of ontology-mediated queries (OMQs) on databases of bounded cliquewidth. Our main contribution is a detailed analysis of the dependence of the running time on the parameter, exhibiting several interesting effects.
  arXiv  Detail & Related papers  (2022-05-04T17:13:08Z)
• Query2Particles: Knowledge Graph Reasoning with Particle Embeddings [49.64006979045662]
  We propose a query embedding method to answer complex logical queries on knowledge graphs with missing edges. The answer entities are selected according to the similarities between the entity embeddings and the query embedding. A complex KG query answering method, Q2P, is proposed to retrieve diverse answers from different areas over the embedding space.
  arXiv  Detail & Related papers  (2022-04-27T11:16:08Z)
• Knowledge Base Question Answering by Case-based Reasoning over Subgraphs [81.22050011503933]
  We show that our model answers queries requiring complex reasoning patterns more effectively than existing KG completion algorithms. The proposed model outperforms or performs competitively with state-of-the-art models on several KBQA benchmarks.
  arXiv  Detail & Related papers  (2022-02-22T01:34:35Z)
• From Conjunctive Queries to Instance Queries in Ontology-Mediated Querying [17.79631575141597]
  We consider ontology-mediated queries based on expressive description logics of the ALC family and (unions) of conjunctive queries. Our results include exact characterizations of when such a rewriting is possible and tight complexity bounds for deciding rewritability.
  arXiv  Detail & Related papers  (2020-10-22T16:40:59Z)
• Answering Counting Queries over DL-Lite Ontologies [0.0]
  We introduce a general form of counting query, relate it to previous proposals, and study the complexity of answering such queries. We consider some practically relevant restrictions, for which we establish improved complexity bounds.
  arXiv  Detail & Related papers  (2020-09-02T11:10:21Z)
• A tetrachotomy of ontology-mediated queries with a covering axiom [1.749935196721634]
  Our concern is the problem of efficiently determining the data complexity of answering queries mediated by description and their optimal rewritings to standard database queries. We focus on Boolean conjunctive-mediated queries called disjunctive sirups (or d-sirups) Some d-sirups only have exponential-size resolution features, some only double-exponential-size positive existential existential-rewritings and single-exprecursive datalog rewritings.
  arXiv  Detail & Related papers  (2020-06-07T14:47:07Z)
• Counting Query Answers over a DL-Lite Knowledge Base (extended version) [14.504450881786214]
  We study the data complexity of query answering over a Knowledge Base (KB) We improve upon existing results by providing a PTIME and coNP lower bounds, and upper bounds in PTIME and LOGSPACE.
  arXiv  Detail & Related papers  (2020-05-12T16:01:09Z)
• Query Focused Multi-Document Summarization with Distant Supervision [88.39032981994535]
  Existing work relies heavily on retrieval-style methods for estimating the relevance between queries and text segments. We propose a coarse-to-fine modeling framework which introduces separate modules for estimating whether segments are relevant to the query. We demonstrate that our framework outperforms strong comparison systems on standard QFS benchmarks.
  arXiv  Detail & Related papers  (2020-04-06T22:35:19Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.