SPARQL Extensions
Owl Datatypes
Native support for the owl:real and
owl:rational datatypes. This
includes the support for comparison and arithmetic operations that involve these datatypes.
Trigonometric and exponential functions
We implement all Trigonometric and exponential functions from XPath and XQuery Functions and Operators 3.1. These functions accept input that are convertible to xsd:double. Following the XPath 3.1 specs, the output of these functions is always xsd:double.
The table below provides an overview of the trigonometric and exponential functions.
Function | Meaning |
|---|---|
PI() | Returns an approximation to the mathematical constant π. |
EXP(?x) | Returns the value of ex. |
EXP10(?x) | Returns the value of 10x. |
LOG(?arg) | Returns the natural logarithm of the argument. |
LOG10(?arg) | Returns the base-ten logarithm of the argument. |
POW(?x, ?y) | Returns the value of xy. |
SQRT(?arg) | Returns the non-negative square root of the argument. |
SIN(?θ) | Returns the sine of the argument. The argument is an angle in radians. |
COS(?θ) | Returns the cosine of the argument. The argument is an angle in radians. |
TAN(?θ) | Returns the tangent of the argument. The argument is an angle in radians. |
ASIN(?arg) | Returns the arc sine of the argument. |
ACOS(?arg) | Returns the arc cosine of the argument. |
ATAN(?arg) | Returns the arc tangent of the argument. |
ATAN2(?y, ?x) | Returns the angle in radians subtended at the origin by the point on a plane with coordinates (x, y) and the positive x-axis. |
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>.