Results 11 to 20 of about 50 (50)
On the primitivity of operators in SPARQL [PDF]
Information Processing Letters, 2014 The paper studies the primitivity of the basic operators UNION, AND, OPTIONAL, FILTER, and SELECT, as they are used in the SPARQL query language. The question of whether one operator can be expressed in terms of the other operators is answered in detail. It turns out that only AND is non-primitive.
Zhang, Xiaowang, Van den Bussche, Jan
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Learning Commonalities in SPARQL [PDF]
, 2017 Finding the commonalities between descriptions of data or knowledge is a foundational reasoning problem of Machine Learning. It was formalized in the early 70's as computing a least general generalization (lgg) of such descriptions. We revisit this well-established problem in the SPARQL query language for RDF graphs.
El Hassad, Sara +2 more
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Streaming SPARQL - Extending SPARQL to Process Data Streams [PDF]
, 2008 A lot of work has been done in the area of data stream processing. Most of the previous approaches regard only relational or XML based streams but do not cover semantically richer RDF based stream elements. In our work, we extend SPARQL, the W3C recommendation for an RDF query language, to process RDF data streams.
André Bolles +2 more
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SPARQL extensions with preferences [PDF]
Proceedings of the 31st Annual ACM Symposium on Applied Computing, 2016 The last decade has witnessed an increasing interest in expressing preferences inside database queries. Even though most of the work has been devoted to relational databases, many proposals have also been made in the Semantic Web area in order to query RDF databases in a flexible way.
Pivert, Olivier +2 more
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, 2015 The original SPARQL proposal was often criticized for its inability to navigate through the structure of RDF documents. For this reason property paths were introduced in SPARQL 1.1, but up to date there are no theoretical studies examining how their addition to the language affects main computational tasks such as query evaluation, query containment ...
Kostylev, E +3 more
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, 2016 This paper presents a thorough study of negation in SPARQL. The types of negation supported in SPARQL are identified and their main features discussed. Then, we study the expressive power of the corresponding negation operators. At this point, we identify a core SPARQL algebra which could be used instead of the W3C SPARQL algebra.
Angles, Renzo, Gutierrez, Claudio
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Sparql-Ld: A Sparql Extension For Fetching And Querying Linked Data
Proceesings of the 14th International Semantic Web Conference - Demonstrations Track (ISWC'15), 2015 SPARQL is a standard query language for retrieving and manipulating RDF data. However, the majority of SPARQL implementations require the data to be available in advance, i.e., to exist in main memory or in a RDF repository (accessible through a SPARQL endpoint).
Fafalios, Pavlos, Tzitzikas, Yannis
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SPARQL with property paths on the Web
Semantic Web, 2017 Linked Data on the Web represents an immense source of knowledge suitable to be automatically processed and queried. In this respect, there are different approaches for Linked Data querying that differ on the degree of centralization adopted. On one hand, the SPARQL query language, originally defined for querying single datasets, has been enhanced with
Giuseppe Pirrò +2 more
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The Multiset Semantics of SPARQL Patterns [PDF]
, 2016 This is an extended and updated version of the paper accepted at the International Semantic Web Conference ...
Claudio Gutierrez, Renzo Angles
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On the Satisfiability Problem for SPARQL Patterns
Journal of Artificial Intelligence Research, 2016 The satisfiability problem for SPARQL 1.0 patterns is undecidable in general, since the relational algebra can be emulated using such patterns. The goal of this paper is to delineate the boundary of decidability of satisfiability in terms of the constraints allowed in filter conditions.
ZHANG, Xiaowang +2 more
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