- From: Jorge Pérez <jperez@ing.puc.cl>
- Date: Thu, 22 Jun 2006 10:19:43 -0400 (CLT)
- To: public-rdf-dawg-comments@w3.org
- Cc: jperez@ing.puc.cl
This is a list of mails between me and FredZ about his (now public) draft on formalization of SPARQL semantics. http://lists.w3.org/Archives/Public/public-rdf-dawg/2006AprJun/0170.html specifically about simple entailment to obtain solutions. - jorge ---------------------------- Mensaje original ---------------------------- Asunto: Re: draft De: Jorge Pérez <jperez@ing.puc.cl> Fecha: Jue, 15 de Junio de 2006, 5:12 pm Para: "Fred Zemke" <fred.zemke@oracle.com> -------------------------------------------------------------------------- I am reading your draft in detail and will give you comments soon... I have just a little question about the definition of solutions consider the dataset D: (a, b, a) (X, b, Y) whit X and Y blank nodes (the rest URIs), how many solutions has the triple pattern ?q b ?q I think that the mappings ?q -> a, ?q -> X, and ?q -> Y are all solutions, am I right? because D simply entails all the following graphs (a, b, a) (X, b, Y) (a, b, a) (X, b, Y) (X, b, X) (a, b, a) (X, b, Y) (Y, b, Y) am I making a mistake? if this is correct, is there a problem in having 3 distincts solutions for this pattern? - jorge ---------------------------- Mensaje original ---------------------------- Asunto: Re: draft De: "Fred Zemke" <fred.zemke@oracle.com> Fecha: Jue, 15 de Junio de 2006, 8:30 pm Para: jperez@ing.puc.cl -------------------------------------------------------------------------- interesting example. I personally hope the answer is that only ?q -> a is a solution, but I have not yet been able to work through all the definitions to decide this one way or the other. I'll let you know when I figure something out. Fred ---------------------------- Mensaje original ---------------------------- Asunto: Re: draft De: Jorge Pérez <jperez@ing.puc.cl> Fecha: Vie, 16 de Junio de 2006, 9:03 am Para: "Fred Zemke" <fred.zemke@oracle.com> -------------------------------------------------------------------------- To avoid this sort of "problems" (surely there are more examples like the one i showed you) in our paper we made the (strong) assumption that the dataset is lean. I think it is a good starting point, this simplify a lot the definitions in the case of simple entailment. Another more theoretical form of defining a solution is that the solution must be the same *as if the dataset were lean*, this avoid the (strong) assumption and pass the problem to implementors... but, who cares about implementation anyway? ;-) - jorge
Received on Thursday, 22 June 2006 15:22:11 UTC