- From: Danny Ayers <danny@panlanka.net>
- Date: Sun, 8 Apr 2001 19:22:04 +0600
- To: <jos.deroo.jd@belgium.agfa.com>, <GK@ninebynine.org>
- Cc: <www-rdf-logic@w3.org>
I'm a little confused here, though I think it's down to the terminology. Surely I can give a triple - subject : a predicate : not object : b and define 'not' as a relation between a and b where if a is true then b is false & vice versa - isn't this negation? surely RDF can express negation in just the same way that saying a = !b would express it? I've a feeling words like 'encoding' and 'expressing' are being used in a very specific way, one that differs from their common English usage - maybe it would help me if someone gave/pointed to definitions? ... <- so irreflexivity is saying that subject and object are <- different (avoiding to write that as a negation) what then is the relation between (subject == object) and (subject != object)? (BTW, this irreflexivity sounds suspiciously like directed graphs) Is there any concensus on TimBL's logical dabblings? : http://www.w3.org/DesignIssues/Toolbox.html --- Danny Ayers http://www.isacat.net <- -----Original Message----- <- From: www-rdf-logic-request@w3.org <- [mailto:www-rdf-logic-request@w3.org]On Behalf Of <- jos.deroo.jd@belgium.agfa.com <- Sent: 08 April 2001 18:25 <- To: GK@ninebynine.org <- Cc: www-rdf-logic@w3.org <- Subject: Re: Reification <- <- <- <- <- something I forgot to mention is that in many cases one can avoid <- negation take for instance the property :sibling <- one cannot be sibling of oneself <- but instead of saying {:sibling1 :equals :sibing2} a log:Falsehood. <- one can assume :sibling an irreflexive property <- in my opinion it's good to be explicit about reflexivity of relations <- i can go from paris to paris and the proof is like a <- *reflection* about what's connected around paris <- (we are thinking about that as *e-circularities*, how you <- write the letter e, you make a kind of cycle but you never <- use a stepwise piece twice) <- <- so irreflexivity is saying that subject and object are <- different (avoiding to write that as a negation) <- <- <- <- <- <- GK@ninebynine.org@INTERNET@w3.org on 04/08/2001 10:29:34 AM <- <- Sent by: www-rdf-logic-request@w3.org <- <- <- To: Jos De_Roo/AMDUS/MOR/Agfa-NV/BE/BAYER@AGFA <- cc: www-rdf-logic@w3.org@INTERNET <- Subject: Re: Reification <- At 10:42 PM 4/6/01 +0100, jos.deroo.jd@belgium.agfa.com wrote: <- >ps you seem to have some interesting points about negation, but I have <- > to re-read them (as I was close to the belief that <- open-world-negation <- > was impossible) <- <- Until this, I never got any sense that open world negation was <- impossible. Rather that it always brought the possibility of <- contradictory <- or inconsistent expression. If I get this right, closed worlds have a <- possibility of setting rules on "valid" expressions such that no two such <- "valid" expressions are contradictory. <- <- Refering to the 1-pager on formal systems that Dan cited a while ago: <- <- [[[ <- % Formal Systems - Definitions <- % (from Ruth E. Davis, Truth, Deduction, and Computation. <- % New York: Computer Science press, 1989.) <- % <- http://www-rci.rutgers.edu/~cfs/305_html/Deduction/FormalSystemDefs.html <- % (c) Charles F. Schmidt <- % Last Modified: Saturday, May 08, 1999 9:07:08 PM GMT <- ]]] <- <- I think this view of a "closed world" might be similar to a "theory". <- <- #g <- <- <- ------------ <- Graham Klyne <- GK@NineByNine.org <- <- <- <-
Received on Sunday, 8 April 2001 09:25:36 UTC