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SPARQL Extensions

Owl Datatypes

Native support for the owl:real and owl:rational datatypes. This inlcudes the support for comparison and arithmetic operations that involve these datatypes.

Extensions Of Operations

The SPARQL standard allows implementations to extend the capabilities of operations (e.g., <, + and =). As described here, these extensions lead to FILTER expressions potentially producing additional results.

Examples of operations that involve extended operations are provided below

Extended comparison operations

xsd:date > xsd:date => xsd:boolean
xsd:duration != xsd:duration => xsd:boolean
owl:real < owl:real => xsd:boolean

Extended arithmetic operations on date and time types

xsd:date - xsd:date => xsd:dayTimeDuration
xsd:dayTimeDuration / xsd:int => xsd:dayTimeDuration

The extended capabilities of the operators are detailed in the chapter Extensions of Operators.

Note: These extensions do not discard any of the expected results.

DESCRIBE Queries

Tentris implements two algorithms for the evaluation DESCRIBE queries.

  • DESCRIBE / DESCRIBE DIRECT
DESCRIBE <http://www.example.org/entity>

DESCRIBE DIRECT <http://www.example.org/entity>

Both queries provided above return the triples of the underlying knowledge graph that have <http://www.example.org/entity> as their subject.

  • DESCRIBE CBD
DESCRIBE CBD <http://www.example.org/entity>

The query provided above returns the Consise Bounded Description of <http://www.example.org/entity>.