- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Mon, 16 Jul 2001 09:01:45 -0400
- To: fikes@KSL.Stanford.EDU
- Cc: horrocks@cs.man.ac.uk, www-rdf-logic@w3.org
From: Richard Fikes <fikes@KSL.Stanford.EDU> Subject: Re: A Problem With The Semantics of DAML+OIL Restrictions Date: Tue, 03 Jul 2001 07:41:15 -0700 > > By the way, I think the model theoretic semantics suffers from the same > problem as the axiomatic semantics in this matter. That is, both of > them seem to treat each constraint in a restriction as sufficient > conditions for membership in the class. The constraints need to be > combined when there is more than one of them in a restriction. > > Richard Richard is correct. There are ``problems'' with the model-theoretic semantics when restrictions have ``multiple'' restrictions on them. However, the problems really amount to a divergence between the intended reading of a restriction with multiple ``restrictions'' on it (form the conjunction of the ``restrictions'') and the specification in the model-theoretic semantics (each ``restriction'' is independantly both necessary and sufficient). However, one way of solving the problem is to leave things are they are! Any restriction that doesn't satisfy the ``one restriction'' property is syntactically valid, but will cause severe semantic difficulties. The axiomatization and the model theoretic semantics could then stay the same. I don't think that the intended reading is viable. Richard pointed out that the intended reading has this non-monotonic component---if you add ``restrictions'' to a restriction its extension changes non-monotonically. pete
Received on Monday, 16 July 2001 09:03:11 UTC