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rdf:nil

Triple-term based reification

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A triple term is a construct defined in the RDF 1.2 Concepts and Abstract - Syntax specification [[RDF12-CONCEPTS]], referring to an RDF triple that - is used as a value, specifically, in the object position of another triple. - Importantly, a triple term does not imply assertion; that is, the triple it - denotes is not necessarily asserted in the RDF graph. This enables the - representation of metadata or commentary about triples that may or may not - be part of the asserted graph content, including potentially contradictory - relationships. For a triple term to be considered an asserted triple, it - must also appear explicitly in an RDF graph as a top-level triple. Otherwise, - it remains unasserted and serves primarily as a reference or subject of metadata.

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A triple term can be the object of a triple whose predicate is +

+ A triple term is a construct defined in [[RDF12-CONCEPTS]], referring to an RDF triple that is used + as a value, specifically, in the object position of another triple. This use represents a reference to a proposition, + and, importantly, a triple term does not by itself imply assertion; that is, the proposition it denotes + is not necessarily a fact asserted by the RDF graph. This is only the case if that triple is also + asserted in the RDF graph — that is, if it is a direct element of that set of triples. + Otherwise, it remains unasserted and serves primarily as a reference or as the subject of metadata. + This enables the representation of metadata or commentary about triples that may or may not be part + of the asserted graph content, including potentially contradictory relationships. +

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+ RDF terms that appear in a triple term have the same denotation as when they appear in an asserted + triple in the graph. For this reason, triple terms are said to be transparent. +

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+ A triple term can be the object of a triple whose predicate is rdf:reifies. In such cases, the resulting triple is referred - to as a reifying triple, and its subject is termed a reifier. The reifier - can be used to make further statements about the triple term.

+ to as a reifying triple, and its subject is + termed a reifier. + When the triple term of a reifying triple also appears in the same graph as an asserted triple, + the subset of triples that share the same + reifier as subject is called a triple annotation. +

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+ When the underlying triple S P O is not asserted in the graph, a reifying triple (i.e., a triple whose predicate is rdf:reifies and whose object is the triple term <<S P O>>) together with further triples that use its reifier as subject constitute a description of the reifier resource, which denotes the proposition expressed by <<S P O>>. This is distinct from a triple annotation as defined in RDF Concepts, which requires that the underlying triple be asserted in the same graph. +

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+ Triple terms always denote abstract, logical propositions, while reifiers may denote a variety of + things related to these propositions (such as a statement or belief that the proposition holds, or + an event or circumstance that makes the proposition true). It is therefore expected that triple + terms are commonly used as objects of reifying triples, and that reifiers (rather than the triple + terms) are used in further descriptions. Because of the diversity of use cases that reifiers aim to + serve, the meaning of the rdf:reifies property is deliberately generic. Multiple, + distinct reifiers may exist for the same proposition (e.g., from different sources or contexts), and, + conversely, one reifier may be used for several propositions. +

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rdfs:Proposition

rdfs:Proposition is the class of reified triples.