W3C home > Mailing lists > Public > www-rdf-logic@w3.org > April 2001

RE: Reification

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>
Message-ID: <EBEPLGMHCDOJJJPCFHEFMEAMDBAA.danny@panlanka.net>
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 GMT

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