Duane,
unfortunately, once I get into a 2d environment, I'm not sure
that "!exists 3d" is meaningful, though it might be in a meta-world
embedding the 2-d world. (01)
Sean Barker
0117 302 8184 (02)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of
> Duane Nickull
> Sent: 31 May 2007 17:10
> To: [ontolog-forum]
> Subject: Re: [ontolog-forum] Ontology,Information Models and
> the 'Real World': Contexts
>
> Sean:
>
> Assuming you have modeled correctly, there should logically
> !exists 3d entity in a 2d environment, should there?
>
> Duane
>
>
> On 5/31/07 1:35 AM, "Barker, Sean (UK)"
> <Sean.Barker@xxxxxxxxxxxxxx> wrote:
>
> >
> > What happens if a context/possible world is such that the
> proposition
> > ceases to be a proposition? That is, it ceases to evaluate
> to true or
> > false? For example, "the volume of a cube is the cube of
> the length of
> > its side" is meaningless in a 2-D world, since there is no
> concept of
> > volume. Similarly (A/B > 1) is meaningless in a context
> where A and B
> > are both zero.
> > The tricky part is that there is no order of evaluation in
> classical
> > logic, so, in the latter case, adding guards on the
> context, such as
> > (A != 0) AND (B != 0), still leaves the combined
> proposition meaningless.
> >
> > Sean Barker
> > 0117 302 8184
> >
> >
> >> -----Original Message-----
> >> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
> >> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf
> Of John F.
> >> Sowa
> >> Sent: 31 May 2007 02:54
> >> To: [ontolog-forum]
> >> Subject: Re: [ontolog-forum] Ontology,Information Models and the
> >> 'Real World': Contexts
> >>
> >>
> >> *** WARNING ***
> >>
> >> This mail has originated outside your organization, either from an
> >> external partner or the Global Internet.
> >> Keep this in mind if you answer this message.
> >>
> >> Wacek, Ken, Pat, Ingvar, et al.,
> >>
> >> I agree that one should use technical terms in a way that stays
> >> fairly close to traditional usage. But the tradition has a lot of
> >> branches. In some branches, a proposition is fairly close to a
> >> sentence, but with the option of considering a restatement in a
> >> different language to be "the same" proposition.
> >>
> >> I take that to mean that a proposition is the language-independent
> >> "meaning" or "intension" of a sentence, and that the truth
> value is
> >> evaluated in terms of some "extension" or universe of discourse.
> >> If somebody changes the extension or universe of
> discourse, then the
> >> truth value may change. But the intension remains fixed.
> >>
> >> That interpretation is consistent with most 20th-century work on
> >> modal and other kinds of intensional logics. Montague,
> for example,
> >> defined the intension of a sentence to be a function that maps
> >> possible worlds to truth values.
> >> Different possible worlds are different extensions, but
> the function
> >> (intension) remains fixed.
> >>
> >> Although I prefer Dunn's semantics of laws and facts to a
> >> Kripke-Montague version with possible worlds, Dunn's approach
> >> produces exactly the same truth values for the same sentences.
> >> That implies that the same sentence with the same intension
> >> (proposition) may have different truth values in different
> >> circumstances. (I don't care whether anyone chooses to
> use the terms
> >> 'possible worlds', 'universes of discourse', or 'contexts'
> for those
> >> circumstances.)
> >>
> >> As Ingvar pointed out, Quine requires propositions to have fixed
> >> truth values. But that follows from the fact that he does
> not allow
> >> different possible worlds or contexts.
> >>
> >> Although I do not like the notion of possible world, I would agree
> >> with the modal logicians that any theory of modal logic
> should permit
> >> the same intension (proposition) to have different truth values in
> >> different extensions (universes of discourse).
> >>
> >> I also agree with Pat that the word 'context' has been used in too
> >> many confused and confusing ways. But I don't like either of the
> >> following ways of talking:
> >>
> >> KC>> In that sense, a change in context BECOMES a
> >>>> change in meaning of a proposition
> >>
> >> PH> No, that is muddled. That is exactly what does NOT happen.
> >>> A proposition never changes its meaning. The SENTENCE >
> >> expresses different propositions.
> >>
> >> I wouldn't say that a proposition changes its meaning
> because I would
> >> prefer to say that a proposition *is* the meaning of a
> sentence. I
> >> also would not say that a sentence whose indexicals were
> resolved to
> >> specific referents could express two or more different
> propositions.
> >>
> >> I'm sure that one can find logicians such as Quine who
> would disagree
> >> with this interpretation. But I believe that it is
> consistent with
> >> those logicians who are more tolerant of modal logic. And since I
> >> want to represent modal sentences in NL, I prefer to accommodate
> >> their usage (even though I use Dunn's semantics rather than
> >> Kripke's).
> >>
> >> John
> >>
> >>
> >> _________________________________________________________________
> >> Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/
> >> Subscribe/Config:
> >> http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
> >> Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
> >> Shared Files: http://ontolog.cim3.net/file/ Community Wiki:
> >> http://ontolog.cim3.net/wiki/ To Post:
> >> mailto:ontolog-forum@xxxxxxxxxxxxxxxx
> >>
> >>
> >>
> >
> > ********************************************************************
> > This email and any attachments are confidential to the intended
> > recipient and may also be privileged. If you are not the intended
> > recipient please delete it from your system and notify the sender.
> > You should not copy it or use it for any purpose nor disclose or
> > distribute its contents to any other person.
> > ********************************************************************
> >
> >
> > _________________________________________________________________
> > Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/
> > Subscribe/Config:
> > http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
> > Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
> > Shared Files: http://ontolog.cim3.net/file/ Community Wiki:
> > http://ontolog.cim3.net/wiki/ To Post:
> > mailto:ontolog-forum@xxxxxxxxxxxxxxxx
> >
>
> --
> ************************************************************
> Sr. Technical Evangelist - Adobe Systems, Inc. *
> Chair - OASIS SOA Reference Model Technical Committee *
> Blog: http://technoracle.blogspot.com *
> My Music: http://www.mix2r.com/audio/by/artist/22ndcentury *
> My Band: http://www.myspace.com/22ndcentury *
> ************************************************************
>
>
> _________________________________________________________________
> Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/
> Subscribe/Config:
> http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
> Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
> Shared Files: http://ontolog.cim3.net/file/ Community Wiki:
> http://ontolog.cim3.net/wiki/ To Post:
> mailto:ontolog-forum@xxxxxxxxxxxxxxxx
>
> (03)
_________________________________________________________________
Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/
Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/
To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx (04)
|