Editing Resource Description Framework (section)

=== Statement reification and context ===
[[Image:Basic RDF Graph.svg|thumb|Basic RDF triple comprising (subject, predicate, object).]]
The body of knowledge modeled by a collection of statements may be subjected to [[Reification (knowledge representation)|reification]], in which each ''statement'' (that is each triple ''subject-predicate-object'' altogether) is assigned a URI and treated as a resource about which additional statements can be made, as in "''Jane says that'' John is the author of document X". Reification is sometimes important in order to deduce a level of confidence or degree of usefulness for each statement.

In a reified RDF database, each original statement, being a resource, itself, most likely has at least three additional statements made about it: one to assert that its subject is some resource, one to assert that its predicate is some resource, and one to assert that its object is some resource or literal. More statements about the original statement may also exist, depending on the application's needs.

Borrowing from concepts available in [[logic]] (and as illustrated in graphical notations such as [[conceptual graphs]] and [[topic map]]s), some RDF model implementations acknowledge that it is sometimes useful to group statements according to different criteria, called ''situations'', ''contexts'', or ''scopes'', as discussed in articles by RDF specification co-editor [[Graham Klyne]].<ref>{{cite web|url=http://www.ninebynine.org/RDFNotes/RDFContexts.html|title=Contexts for Information Modelling in RDF|first=Graham|last=Klyne|website=ninebynine.org}}</ref><ref>{{cite web|url=http://www.ninebynine.org/RDFNotes/UsingContextsWithRDF.html|title=RDF Contexts - provenance and partial knowledge|website=ninebynine.org |date=March 13, 2002 |first1=Graham |last1=Klyne |url-status=live |archive-url=https://web.archive.org/web/20230729162843/http://www.ninebynine.org/RDFNotes/UsingContextsWithRDF.html |archive-date= Jul 29, 2023 }}</ref> For example, a statement can be associated with a context, named by a URI, in order to assert an "is true in" relationship. As another example, it is sometimes convenient to group statements by their source, which can be identified by a URI, such as the URI of a particular RDF/XML document. Then, when updates are made to the source, corresponding statements can be changed in the model, as well.

Implementation of scopes does not necessarily require fully reified statements. Some implementations allow a single scope identifier to be associated with a statement that has not been assigned a URI, itself.<ref>{{cite web|url=http://uche.ogbuji.net/tech/akara/nodes/2003-01-01/scopes|title=The concept of 4Suite RDF scopes |website=Uche Ogbuji |url-status=dead |archive-url= https://web.archive.org/web/20081208114927/http://uche.ogbuji.net/tech/akara/nodes/2003-01-01/scopes |archive-date= Dec 8, 2008 }}</ref><ref>{{cite web|url=http://librdf.org/notes/contexts.html|title=Redland Notes - Contexts|website=Redland RDF Libraries |date=2004 |url-status=live |archive-url= https://web.archive.org/web/20230729162841/https://librdf.org/notes/contexts.html |archive-date= Jul 29, 2023 }}</ref>  Likewise ''named graphs'' in which a set of triples is named by a URI can represent context without the need to reify the triples.<ref>{{cite web|url=http://www.w3.org/2004/03/trix/|title=Named Graphs / Semantic Web Interest Group|website=W3C |url-status=live |archive-url=https://web.archive.org/web/20231001045448/https://www.w3.org/2004/03/trix/ |archive-date= Oct 1, 2023 }}</ref>