Formulates advanced queries on data containing blank nodes. – Linked Data for Professional Education

Expressive Languages for Querying the Semantic Web

Abi Evans — Tue, 15 Sep 2015 02:33:09 +0000

SPARQL 1.1 was recently released, which includes entailment regimes for
RDFS and OWL vocabularies and a mechanism to express navigation patterns through regular expressions. Unfortunately, there are still some useful navigation patterns that cannot be expressed in SPARQL 1.1, and the language lacks of a general mechanism to express recursive queries. To the best of the authors' knowledge, there is no RDF query language that combines the above functionalities, and which can also be evaluated efficiently. It is the aim of this work to fill this gap.

URL: http://ciws.cl/media/pdf/pods14.pdf
Keywords: RDF Schema, SPARQL, Web Ontology Language (OWL), Entailment regimes, Datalog
Author: Pieris, Andreas
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P30M
Educational use: instruction
Educational audience: teacher-educationSpecialist
Interactivity type: expositive

Using SPARQL with RDFS and OWL Entailment

Abi Evans — Tue, 15 Sep 2015 02:33:08 +0000

This chapter accompanied the lecture on SPARQL with entailment
regimes given at the 7th Reasoning Web Summer School in Galway, Ireland, 2011. It first introduces the main features of SPARQL as a query language. Then, in order to define the semantics of a query, it shows how a query can be translated to an abstract query, which can then be evaluated according to SPARQL’s query evaluation mechanism. This chapter also briefly introduce the features of SPARQL 1.1, which was under development at the time of this writing.

URL: http://www.uni-ulm.de/fileadmin/website_uni_ulm/iui.inst.090/Publikationen/2011/Glim11a.pdf
Keywords: Description Logic, Entailment Regimes, Basic Graph Pattern (BGP), Web Ontology Language (OWL), RDF Schema, Sub-graph matching, SPARQL
Author: Glimm, Birte
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P2H
Educational use: instruction
Educational audience: generalPublic
Interactivity type: expositive

SPARQL Beyond Subgraph Matching

Abi Evans — Tue, 15 Sep 2015 02:33:08 +0000

This paper describes the extension of the Semantic Web query language SPARQL by defining the semantics of SPARQL queries under the entailment regimes of RDF, RDFS, and OWL. It reviews the conditions that SPARQL
imposes on such extensions, discusses the practical difficulties of this task, and explicates the design choices underlying our proposals. In addition, it includes an overview of current implementations and their underlying techniques.

URL: https://www.cs.ox.ac.uk/files/3130/paper.pdf
Keywords: Basic Graph Pattern (BGP), SPARQL, RDF Schema, Web Ontology Language (OWL), Entailment Regimes
Author: Krötzsch, Markus
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P30M
Educational use: instruction
Educational audience: professional
Interactivity type: expositive

Schema-Agnostic Query Rewriting in SPARQL 1.1

Abi Evans — Tue, 15 Sep 2015 02:33:08 +0000

SPARQL 1.1 supports the use of ontologies to enrich query results with logical entailments, and OWL 2 provides a dedicated fragment OWL QL for this purpose. Typical implementations use the OWL QL schema to rewrite a conjunctive query into an equivalent set of queries, to be answered against
the non-schema part of the data. With the adoption of the recent SPARQL 1.1
standard, however, RDF databases are capable of answering much more expressive queries directly, and this paper asks how this can be exploited in query rewriting.

URL: http://korrekt.org/papers/Bischof-Kroetzsch-Polleres-Rudolph_Schema-Agnostic-Query-Rewriting_ISWC-2014-TR.pdf
Keywords: Ontology-Based Data Access (OBDA), Entailment Regimes, Web Ontology Labnuage (OWL), Ontology, SPARQL
Author: Bischof, Stefan
Publisher: Krötzsch, Markus
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P60M
Educational use: instruction
Educational audience: student
Interactivity type: expositive

Foundations of Semantic Web Technologies: SPARQL Entailment Regimes

Abi Evans — Tue, 15 Sep 2015 02:33:08 +0000

Slides covering the following topics: SPARQL can now be used with RDF Schema, OWL, and RIF semantics. Entailment Regimes overwrite evaluation of basic graph patterns. Property Paths from SPARQL Query 1.1 can be problematic. Definition of solutions (relatively) general: a) work for sub-graph matching/simple entailment and b) OWL’s Direct Semantics needs extra conditions/definitions. Implementation and efficiency for OWL can be problematic – necessitates OWL 2 Profiles.

URL: http://www.inf.tu-dresden.de/content/institutes/ki/cl/study/summer14/fswt/slides/FSWT2014-L17-SPARQL-Entailment.pdf
Keywords: RDF Schema, Entailment Regimes, Rule Interchange Format (RIF), Web Ontology Language (OWL), Skolemisation, Basic Graph Pattern (BGP)
Author: Rudolph, Sebastian
Publisher: Dresden University of Technology (TUD)
Date created: 2014-06-18 04:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P40M
Educational use: instruction
Educational audience: student
Interactivity type: expositive

SPARQL 1.1 Entailment Regimes

Abi Evans — Tue, 15 Sep 2015 02:33:08 +0000

There are different possible ways of defining a basic graph pattern matching extension for an entailment relation. This document specifies one such way for a range of standard semantic web entailment relations. Such extensions of the SPARQL semantics are called entailment regimes within this document. An entailment regime defines not only which entailment relation is used, but also which queries and graphs are well-formed for the regime, how the entailment is used and what kinds of errors can arise.

URL: http://www.w3.org/TR/2012/CR-sparql11-entailment-20121108/
Keywords: SPARQL, Entailment Regimes, Web Ontology Language (OWL), RDF Schema, Rule Interchange Format (RIF)
Author: Ogbuji, Chimezie
Publisher: W3C
Date created: 2012-11-08 05:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P60M
Educational use: instruction
Educational audience: student
Interactivity type: expositive

SPARQL: Querying the Web of Data

Abi Evans — Thu, 13 Aug 2015 13:45:22 +0000

This slide-set aims to introduce the RDF query language SPARQL "from a user's perspective". This presentation predates the introduction of SPARQL 1.1, but may still serve as a good introduction to the query language because it covers many, if not a majority, of basic operations.

URL: http://www.slideshare.net/olafhartig/an-introduction-to-sparql?related=2
Keywords: SPARQL, SPARQL endpoint, Constraints, Negation
Author: Hartig, Olaf
Publisher: Humboldt University of Berlin
Date created: 2009-04-07 07:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P45M
Educational use: instruction
Interactivity type: expositive

From SQL to SPARQL

Abi Evans — Thu, 13 Aug 2015 03:26:21 +0000

This presentation gives an overview of the SPARQL query language and how it is different than SQL, which is used for relational databases. Mentions several software tools for SPARQL support: Apache Jena; Redland; Twinkle. Predates the adoption of SPARQL 1.1, but still useful as a basic introduction to simple queries.

URL: http://www.slideshare.net/grecognos/from-sql-to-sparql?related=1
Keywords: SQL, SPARQL
Author: Miron, Dia
Publisher: Roth, George
Date created: 2011-04-17 07:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P20M
Educational audience: student
Interactivity type: expositive

Simple SPARQL Tutorial: Understanding Blank Nodes

Abi Evans — Thu, 13 Aug 2015 03:26:20 +0000

This tutorial explains the purpose of blank nodes and gives a brief demonstration of their use.

URL: https://www.youtube.com/watch?v=jnL9ZqLHJj0
Keywords: 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

Introduction to SPARQL

Abi Evans — Thu, 13 Aug 2015 03:26:20 +0000

A simple (yet thorough) introduction to SPARQL query language based on the W3C documentation. Focuses on aspects of the query language present in SPARQL 1.0 and does not include features added in SPARQL 1.1 Update.

URL: http://www.slideshare.net/szeke/introduction-to-sparql?next_slideshow=2
Keywords: SPARQL, Negation, BIND
Author: Szekely, Pedro
Date created: 2013-05-21 07:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P45M
Educational use: instruction
Educational audience: professional
Interactivity type: expositive