| http://www.w3.org/...qTerms.rdf#answer
| -
The term “rules” in the context of the Semantic Web refers to elements of logic programming and rule based systems bound to Semantic Web data. Rules offer a way to express, for example, constraints on the relationships defined by by RDF, or may be used to discover new, implicit relationships.
Various rule systems (production rules, Prolog-like systems, etc) are very different from one another, and it is not possible to define one rule language to encompass them all. However, it is possible to define a “core” that is essentially understood by all rule systems. This core is based on restricted kind of rule, called a “Horn” rule, which (like most rules) has the form “if conditions then consequence”, but it places certain restrictions on the kinds of conditions and consequences that can be used.
A general example may help. While integrating data coming from different sources, the data may include references to persons, their name, homepage, email addresses, etc. However, the data does not say when two persons should be considered as identical, although this is clearly important for a full integration. An extra condition can be expressed stating that “if two persons have similar names, home pages, and email addresses, then they are identical”. Such condition can be naturally expressed with Horn rules.
The Rule Interchange Format (RIF) Working Group is currently working on a precise definition of this “core” Rule language, on ways to extend this rule language to various variants (production rules, logic programming, etc), to exchange expression of rules among systems, and to define the precise relationships of these rules with OWL ontologies and their usage with RDF triples.
-
The term “rules” in the context of the Semantic Web refers to elements of logic programming and rule based systems bound to Semantic Web data. Rules offer a way to express, for example, constraints on the relationships defined by by RDF, or may be used to discover new, implicit relationships.
Various rule systems (production rules, Prolog-like systems, etc) are very different from one another, and it is not possible to define one rule language to encompass them all. However, it is possible to define a “core” that is essentially understood by all rule systems. This core is based on restricted kind of rule, called a “Horn” rule, which (like most rules) has the form “if conditions then consequence”, but it places certain restrictions on the kinds of conditions and consequences that can be used.
A general example may help. While integrating data coming from different sources, the data may include references to persons, their name, homepage, email addresses, etc. However, the data does not say when two persons should be considered as identical, although this is clearly important for a full integration. An extra condition can be expressed stating that “if two persons have similar names, home pages, and email addresses, then they are identical”. Such condition can be naturally expressed with Horn rules.
The Rule Interchange Format (RIF) Working Group is currently working on a precise definition of this “core” Rule language, on ways to extend this rule language to various variants (production rules, logic programming, etc), to exchange expression of rules among systems, and to define the precise relationships of these rules with OWL ontologies and their usage with RDF triples.
|
![[RDF Data]](/fct/images/sw-rdf-blue.png)
![[cxml]](/fct/images/cxml_doc.png)
![[csv]](/fct/images/csv_doc.png)
![[text]](/fct/images/ntriples_doc.png)
![[turtle]](/fct/images/n3turtle_doc.png)
![[ld+json]](/fct/images/jsonld_doc.png)
![[rdf+json]](/fct/images/json_doc.png)
![[rdf+xml]](/fct/images/xml_doc.png)
![[atom+xml]](/fct/images/atom_doc.png)
![[html]](/fct/images/html_doc.png)