Editing Reified Statements
Reified statements are very useful to attach information about a statement, e.g. to annotate who has created the statement, or to attach other metadata for n-ary relationships. RDF Schema defines a standard class rdf:Statement and corresponding properties to enable people to talk about statements. However, tool support for editing these statements has been poor and therefore rdf:Statement does not seem to be used very much - at least not in hand-crafted ontologies.
This afternoon I have experimented with support for editing reified relationships in TopBraid Composer. The outcome will be available in version 1.1.5 soon.
Whenever you want to do a statement about a statement, you can now reify it using the statement's drop down menu:
In the following dialog you can assign template annotations to the new rdf:Statement. In the example below, the system will automatically insert the given dc:creator and insert the current date as a value of dc:date.
Later, if a statement is reified, then the tool tip text of the icon's statement will show the properties of the rdf:Statement:
It goes without saying that you can now use all the other Composer features such as SPARQL to find statements with certain characteristics, attach TODO tags to them etc.
There is more work on this in the queue, for example to support the same approach with other types of reified relationships, and to automatically manage such reifications as discussed in a previous posting. In the meantime I'd appreciate feedback on the usefulness of this approach :)