Uses a temporary variable to extend a query. – Linked Data for Professional Education https://ld4pe.dublincore.org Learning resources tagged by competency Thu, 19 Nov 2020 14:45:03 +0000 en-US hourly 1 https://wordpress.org/?v=4.9.16 On the Semantics of SPARQL Queries with Optional Matching under Entailment Regimes https://ld4pe.dublincore.org/learning_resource/on-the-semantics-of-sparql-queries-with-optional-matching-under-entailment-regimes-2/ Sat, 16 Jan 2016 13:43:29 +0000 https://ld4pe.dublincore.org/learning_resource/on-the-semantics-of-sparql-queries-with-optional-matching-under-entailment-regimes-2/ This presentation covers the semantics of SPARQL queries with optional matching features under entailment regimes. It argues that normative semantics may lead to answers that are in conflict with the intuitive meaning of optional matching, where unbound variables naturally represent unknown information. The presenters propose an extension of the SPARQL algebra that addresses these issues and is compatible with any entailment regime satisfying the minimal requirements given in the normative specification. They argue that this solution comes at no cost for regimes with an entailment relation of reasonable complexity and that it preserves the known properties of optional matching that are commonly exploited for static analysis and optimization.

URL: http://videolectures.net/iswc2014_kostylev_sparql_queries/
Keywords: Entailment regimes, Unbound variable, Normative semantics, Web Ontology Language (OWL), Strict semantics
Author: Kostylev, Egor
Date created: 2014-12-19 05:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P15M

]]> Simple SPARQL Tutorial: Using the UNION Keyword https://ld4pe.dublincore.org/learning_resource/simple-sparql-tutorial-using-the-union-keyword/ https://ld4pe.dublincore.org/learning_resource/simple-sparql-tutorial-using-the-union-keyword/#respond Thu, 13 Aug 2015 03:26:19 +0000 https://ld4pe.dublincore.org/learning_resource/simple-sparql-tutorial-1429-using-the-union-keyword/ Tutorial showing how to modify a query to combine the results of two separate graph patterns (or conditions) using the UNION keyword. The topic is discussed further in the next video of the series.

URL: https://www.youtube.com/watch?v=sEBfxZbEEtc
Keywords: SPARQL
Author: Sadawi, Noureddin
Date created: 2014-03-03 07:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P10M

]]> https://ld4pe.dublincore.org/learning_resource/simple-sparql-tutorial-using-the-union-keyword/feed/ 0 Simple SPARQL Tutorial: Searching with Blank Nodes https://ld4pe.dublincore.org/learning_resource/simple-sparql-tutorial-searching-with-blank-nodes/ https://ld4pe.dublincore.org/learning_resource/simple-sparql-tutorial-searching-with-blank-nodes/#respond Thu, 13 Aug 2015 03:26:18 +0000 https://ld4pe.dublincore.org/learning_resource/simple-sparql-tutorial-2429-searching-with-blank-nodes/ Building on the previous tutorial of the series, this tutorial shows how to construct and run SELECT queries when a dataset has blank nodes.

URL: https://www.youtube.com/watch?v=y2jbA2pQL44
Keywords: Skolemization, SPARQL, Blank nodes
Author: Sadawi, Noureddin
Date created: 2014-03-03 07:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P10M

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