Each statement in a model has a corresponding resource representing the reified statement. These are the statements regarded as facts by the model agent. A spelled out reified statement is not regarded as a fact, and is called a citation.
Citations are statings, even if the model or agent of the stating is unknown.
If the URI of the stating is specified, it could be the URI of a resource actually stated in another model. In this case, the origin is known and the properties of the stating (the predicate, subject, object, etc) could be left out.
In the common case, the original URI of the stating cited is unknown. In this case, the stating will be placed in a special model created only for citations contained in the specific model.
The cited stating can be traced back to the model in which it
was cited by the four reification statings that
do belong to that model. We may avoid creating
a separate node for each of the four
statings of the reification, in order to save space. The origin
of the citation could be known by metadata for the special
citation model. The model could have a quotedIn
property. A FACT slot (for the node) will not
be used.
A citation could, instead or in addition to the correct stating
URI, include enough data to infere
which stating is cited. This could for example be done by
adding the ls:model property. The citation can
then be coupled to the original stating by use of aliasing. The alias statement will be placed
in a model according to the inference.
Not implemented