Re: SPARQL query equality and "equivalence"...

[Andy Seaborne]

I also don't know how I can plug a new QueryEngineHTTP into ARQ, if it's
possible.

Just on this part (more later):

arq.examples.MyQueryEngine

There's a factory/implementation pair.  The factory checking is a good 
place to see if it's in the query is in the preevaluated results cache.

        Andy