- From: Chris Welty <cawelty@frontiernet.net>
- Date: Wed, 10 May 2006 20:58:37 -0400
- To: Sandro Hawke <sandro@w3.org>
- CC: public-rif-wg@w3.org
Sandro Hawke wrote: > I was asked to clarify my use of the term "sound" in the context of RIF. > > This came up because I proposed a requirement "Sound reasoning with > unknown dialects", or more fully, "RIF Core must allow sound reasoning > with unknown dialects." [1] > > I think this is one of the main requirements which will constraint the > extensibility design. The application context I'm imagining is use case > 8, a query-answering process using deduction rules (database views) > coming from a variety of sources. My requirement here is that I be able > to incorporate rulesets which include unknown extensions, and to know > that even in the worst case I will not get wrong answers. > > In other word, I might incorporate a ruleset that includes this rule: > > phoneNumberOfAssistant(Boss,Number) :- > assistant(Boss,Assistant), > phoneNumber(Assistant,Number). > > and also > > assistant(Boss,Assistant), > phoneNumber(Assistant,Number) :- > phoneNumberOfAssistant(Boss,Number). > > The first rule is a normal Horn clause. The second is not. I'm not > sure what it is, really. :-) And I don't want my program to have to > know either. I want it to be able to safely include the ruleset > containing both these rules and make inferences which will be sound, > even though it has no idea what the second rule is supposed to mean. It > will certainly be incomplete because of not knowing what the second rule > means, if it wasn't incomplete already. > Regardless of what Francois thinks "sound" means, this argument of yours above seems to make assumptions about monotonicty and negation. What if e.g. the rule you understand expresses a default and the rule you don't understand expresses an exception? You may draw a conclusion that is incorrect, i.e. unsound wrt the semantics of the unknown dialect. -Chris > I believe this use of the word "sound" is normal and correct for logic. > I'm asking that the conclusions of an inference procedure follow > logically from its premise. The twist here is that the premise is > written in RIF and may have parts which are opaque extensions as far as > the inference procedure is concerned. > > Please note also that I understand many people invision using RIF only > through translators, but I don't think that affects this discussion at > all. For my purposes, the Translator+InferenceEngine can be thought of > as an InferenceEngine which operates on RIF. > > Also, I understand that I'm only thinking about deduction rules here, > but I think this requirement has an extension which covers production > rules as well, I'm just not as clear about how to state it. > > There are negation/close-world situations in which this requirement may > not be attainable. I'm concerned about that. Perhaps these cases can > be somehow identified, so that users can be warner or automated > processes can avoid the unsound-in-this-situation constructs. > > Does that make sense? > > Is this a requirement you would support? > > -- Sandro > > (I believe this e-mail addresses action items 6 and 7) > > [1] http://www.w3.org/2005/rules/wg/wiki/Sound_reasoning_with_unknown_dialects > > > > > > -- Dr. Christopher A. Welty IBM Watson Research Center +1.914.784.7055 19 Skyline Dr. cawelty@frontiernet.net Hawthorne, NY 10532 http://www.research.ibm.com/people/w/welty
Received on Thursday, 11 May 2006 00:58:47 UTC