It's ugly and more bugs than code at the moment, but if you do this:
CREATE TABLE semantics (create_page TEXT, source_page TEXT, relation TEXT, target_page TEXT); CREATE INDEX i_create_page ON semantics(create_page(50)); CREATE INDEX i_source_page ON semantics(source_page(50)); CREATE INDEX i_target_page ON semantics(target_page(50));
and then add the attached file to LocalSettings.php (tested w/ mediawiki 1.9.3), you can create links like [[x::R::y]] on any MediaWiki page to indicate that X relates to Y.
Semantic data for each page (even pages that don't exist yet) is displayed at the bottom of the page.
I tried to edit existing Semantic Mediawiki code for this, but it really seems married to a "page can only create semantic data for itself" philosophy.
If there's enough/any interest here, please let me know, and we can SourceForge this or something (my goals are in the comments near the end of the attached file)