Bagging the DL-Lite family further
Ontology-based data access (OBDA) is a popular approach for integrating and querying multiple data sources by means of an ontology, which is usually expressed in a description logic (DL) of DL-Lite family. The conventional semantics of OBDA and DLs is set-based—that is, duplicates are disregarded. T...
| Main Authors: | , , , , , |
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| Format: | Conference item |
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CEUR Workshop Proceedings
2019
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| _version_ | 1797076429760888832 |
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| author | Cima, G Nikolaou, C Kostylev, E Kaminski, M Grau, B Horrocks, I |
| author_facet | Cima, G Nikolaou, C Kostylev, E Kaminski, M Grau, B Horrocks, I |
| author_sort | Cima, G |
| collection | OXFORD |
| description | Ontology-based data access (OBDA) is a popular approach for integrating and querying multiple data sources by means of an ontology, which is usually expressed in a description logic (DL) of DL-Lite family. The conventional semantics of OBDA and DLs is set-based—that is, duplicates are disregarded. This disagrees with the standard database bag (multiset) semantics, which is especially important for the correct evaluation of aggregate queries. In this article, we study two variants of the bag semantics for query answering over DL-LiteF , extending basic DL-Litecore with functional roles. For our first semantics, which follows the semantics of primary keys in SQL, conjunctive query (CQ) answering is coNP-hard in data complexity in general, but it is in TC0 for the restricted class of rooted CQs; such CQs are also rewritable to the bag relational algebra. For our second semantics, the results are the same except that TC0 membership and rewritability hold only for the restricted class of ontologies identified by a new notion of functional weak acyclicity |
| first_indexed | 2024-03-07T00:03:38Z |
| format | Conference item |
| id | oxford-uuid:76d28b19-172a-4968-b45c-f4ab907d84f8 |
| institution | University of Oxford |
| last_indexed | 2024-03-07T00:03:38Z |
| publishDate | 2019 |
| publisher | CEUR Workshop Proceedings |
| record_format | dspace |
| spelling | oxford-uuid:76d28b19-172a-4968-b45c-f4ab907d84f82022-03-26T20:18:51ZBagging the DL-Lite family furtherConference itemhttp://purl.org/coar/resource_type/c_5794uuid:76d28b19-172a-4968-b45c-f4ab907d84f8Symplectic Elements at OxfordCEUR Workshop Proceedings2019Cima, GNikolaou, CKostylev, EKaminski, MGrau, BHorrocks, IOntology-based data access (OBDA) is a popular approach for integrating and querying multiple data sources by means of an ontology, which is usually expressed in a description logic (DL) of DL-Lite family. The conventional semantics of OBDA and DLs is set-based—that is, duplicates are disregarded. This disagrees with the standard database bag (multiset) semantics, which is especially important for the correct evaluation of aggregate queries. In this article, we study two variants of the bag semantics for query answering over DL-LiteF , extending basic DL-Litecore with functional roles. For our first semantics, which follows the semantics of primary keys in SQL, conjunctive query (CQ) answering is coNP-hard in data complexity in general, but it is in TC0 for the restricted class of rooted CQs; such CQs are also rewritable to the bag relational algebra. For our second semantics, the results are the same except that TC0 membership and rewritability hold only for the restricted class of ontologies identified by a new notion of functional weak acyclicity |
| spellingShingle | Cima, G Nikolaou, C Kostylev, E Kaminski, M Grau, B Horrocks, I Bagging the DL-Lite family further |
| title | Bagging the DL-Lite family further |
| title_full | Bagging the DL-Lite family further |
| title_fullStr | Bagging the DL-Lite family further |
| title_full_unstemmed | Bagging the DL-Lite family further |
| title_short | Bagging the DL-Lite family further |
| title_sort | bagging the dl lite family further |
| work_keys_str_mv | AT cimag baggingthedllitefamilyfurther AT nikolaouc baggingthedllitefamilyfurther AT kostyleve baggingthedllitefamilyfurther AT kaminskim baggingthedllitefamilyfurther AT graub baggingthedllitefamilyfurther AT horrocksi baggingthedllitefamilyfurther |