- From: Bijan Parsia <bparsia@cs.man.ac.uk>
- Date: Fri, 25 Aug 2006 17:57:52 +0100
- To: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Sigh. Got the reply header wrong. Cheers, Bijan. Begin forwarded message: > From: Bijan Parsia <bparsia@cs.man.ac.uk> > Date: August 25, 2006 12:37:18 PM BDT > To: Pat Hayes <phayes@ihmc.us> > Subject: Re: ACTION item(s): definition(s) and an algorithm for > postprocessing minimization > > On Aug 24, 2006, at 5:52 PM, Pat Hayes wrote: > >>> On Aug 21, 2006, at 10:53 AM, Seaborne, Andy wrote: >>> >>>> Bijan Parsia wrote: > [snip] >>>>> So, first qualification: These algorithms are only minimizing >>>>> with respect to BNodes. You have to plug in your own account of >>>>> literals. I use "row" for "answer" avoid confusion: >>>>> DEFINITION 1: Answer graph template >>>>> Let A be an answer set and Avar be the set of column headings >>>>> of A. >>>>> The answer graph template of A is the set of triple patterns, >>>>> such that: >>>>> {tp | _:row ('http://var.org/#" ++ var) var. & var \in Avar} >>>> ^^^ >>>> value? >>> >>> I just needed a random URI prefix. Substitute any you like. >> >> We did once consider a proposal to have a special 'anonymous' >> prefix, basically an IRI space solely for skolem names, as part of >> the spec. > > This isn't the same. The prefix is used to turn a query variable > name into a property. There are no *values* in the picture yet. By > "random" I just mean I needed *any* one in order to form the > template and then the analogous graph. If you skolemed the bnodes > in this way, the resulting graph would *not* be lean (I believe). > >> That idea kind of died, I think (?) because it was felt to be >> artificial and not in the IRI spirit of rock-solid eternal >> universal identifiers that retain their meaning throughout the >> known universe, > > Ah, it died of foolish prejudice. > >> but it might be worth reconsidering it. There are emails about >> this in the archive somewhere but I confess I can't actually find >> them now. >> >>>> (Just to show I'm reading this all!) >>> >>> Heh. >>> >>> Oh, if we had (do we have?) CONSTRUCT DISTINCT, I would >>> personally expect a lean graph as output. >> >> I agree, if we have this, but I hope we don't :-) > > Well, I was trying to pump the intuition that DISTINCT was > connected to leanness of output, not of input. I see I've succeeded. > > Cheers, > Bijan.
Received on Friday, 25 August 2006 16:57:54 UTC