- From: Dan Connolly <connolly@w3.org>
- Date: Thu, 03 Feb 2005 18:39:25 -0600
- To: Pat Hayes <phayes@ihmc.us>
- Cc: www-archive@w3.org, Eric Prud'hommeaux <eric@w3.org>, Jos De Roo <jos.deroo@agfa.com>
Pat, I can't quite put my finger on it, but I'm afraid there are some serious architectural use/mention issues with operators like BOUND, URI-equal, isURI, and isBlank http://www.w3.org/2001/sw/DataAccess/issues#useMentionOp As I see the architecture, a query plays the role of a conjecture to be proved. A query solution is a sketch of a proof. If I write SELECT ?who WHERE ?who foaf:name "Dan Connolly" it's akin to asking a theorem prover to prove: exists (x) such that foaf:name(x, "Dan Connolly") The solution "?who binds to <danshomePage#topic>" is a sketch of a proof (I think the literature uses the term "witness" for this sort of thing). Now I can't imagine how to turn SELECT ?who WHERE ?who foaf:homePage ?x AND isURI(?x) into a conjecture to be proved by a theorem prover. isURI() is not a function of objects in the domain of discourse, but an operator that distinguishes one sort of term from another. We might have <dansHomePage#topic> owl:sameAs _:somebody . and by definition isURI(<dansHomePage#topic>) but not isURI(_:somebody) This sets off flags in my mind, but I can't state, in black-and-white, testable ways that matter to applications and coders, why it matters. Does it worry you? p.s. formally this is a WG issue http://www.w3.org/2001/sw/DataAccess/issues#useMentionOp In Helsinki, we has some relevant discussion and made a nearby decision, but it wasn't explicitly a decision to close this issue. RESOLVED: BOUND keyword and no UNSAID to address common UNSAID issues. KendallC abstaining http://www.w3.org/2001/sw/DataAccess/ftf4.html#item04 I'm trying to figure out whether to open substantive discussion of this useMentionOp issue or just say "oh... yeah, we meant to close that one too, didn't we?" -- Dan Connolly, W3C http://www.w3.org/People/Connolly/ D3C2 887B 0F92 6005 C541 0875 0F91 96DE 6E52 C29E
Received on Friday, 4 February 2005 00:39:27 UTC