I think there should be an option in Special:Ask to search for pages that contain the attributes in the query not just directly but also indirectly through links.
For example: if you run the search [[located in::New York (state)]] in http://ontoworld.org/wiki/Special:Ask
You will get New York but not Brooklyn.
It is true that Brooklyn could have been found with the nested query [[Burrough of::<q>[[located in::New York (state)]]</q>]] but this requires the human user entering the query to know about this possible indirect membership between some cities (Brooklyn) and states.
A more friendlier solution would be to have a check-box in Special:Ask that once turned will allow the user to enter the simpler query [[New York (state)]] and the result would be all pages that have a relation to “New York (state)” directly or indirectly through links to other pages.
I’ve reached this idea while working on my project in which I try to use SMW as a repository of accounting information.