- From: Chimezie Ogbuji <ogbujic@ccf.org>
- Date: Thu, 25 Mar 2010 10:24:47 -0400
- To: "Axel Polleres" <axel.polleres@deri.org>, "SPARQL Working Group" <public-rdf-dawg@w3.org>
On 3/25/10 4:34 AM, "Axel Polleres" <axel.polleres@deri.org> wrote: > "Without appropriate safety conditions, cyclic references can rule out the > existence of a single intended Herbrand model of the combination and indeed > various stratification and stable model theories [STABLEMODEL] have been > defined in the literature that use a dependency graph to determine if a > ruleset is stratified and incorporate the restricted use of built-in function > symbols that allow the truth of a predicate to be well-defined by an external > procedure. This entailment regime restricts the legal graphs to only those > that refer to strongly safe RIF core documents. This excludes the use of > negated (non-monotonic) atoms and cyclic references between terms in > built-ins." > > I think this paragraph might confuse. Stable models, stratification, etc. are > only vaguely related to the issue we face here, since they are usually only of > interest in the context of rule languages with (non-monotonic) negation. The cyclic restrictions of stable models and stratification are of the same kind used in the RIF Core strong safety conditions (whether or not they are used for negation). This paragraph (and reference) was meant to describe how (traditionally) these kind of restrictions are used and how they are leveraged to ensure finiteness. -- Chime =================================== P Please consider the environment before printing this e-mail Cleveland Clinic is ranked one of the top hospitals in America by U.S.News & World Report (2009). Visit us online at http://www.clevelandclinic.org for a complete listing of our services, staff and locations. Confidentiality Note: This message is intended for use only by the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient or the employee or agent responsible for delivering the message to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please contact the sender immediately and destroy the material in its entirety, whether electronic or hard copy. Thank you.
Received on Thursday, 25 March 2010 14:25:42 UTC