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

Re: What do the ontologists want

From: pat hayes <phayes@ai.uwf.edu>
Date: Fri, 18 May 2001 16:29:02 -0500
Message-Id: <v04210132b72b3b86f3db@[205.160.76.183]>
To: "Seth Russell" <seth@robustai.net>
Cc: www-rdf-logic@w3.org
>From: "pat hayes" <phayes@ai.uwf.edu>
>
> > But whatever you call it, the point is that the *logical* syntax in
> > this case is NOT the triples, but these more complicated structures
> > that are being implemented as sets of triples. So we need to somehow
> > specify the rules for what counts as being well-structured (not every
> > set of triples will be) and we will probably need a few
> > datastructuring primitives (like end-of-chain markers, cf. Lisp NIL.)
> > In other words, we will have to do a little work. Just a tad, but we
> > will need to do it. Sorry if that's not anarchic enough. (There isnt
> > anything odd or exotic about all this, let me emphasize: its is just
> > ordinary bread-and-butter datastructure design. We really do teach it
> > to our undergraduates.)
>
>Yes triples combine to form more complex structures.  The individual triples
>that compose those larger structures cannot be isolated and mean anything.
>But it is a slippery slope as to where you draw the line ... and i think
>that is true of any  kind of logic that deals with reality.

Most (all?) of the logics I know draw this particular line very 
sharply, so I don't see it as very slippery at all.

>In other words
>it is the behavior of the entire graph (model) that has meaning, not an
>individual piece.

Well, scrub round 'behavior' (graphs don't behave. At best, an 
interpreter of a graph might behave, but thats not the meaning.). And 
the basic idea of 'language' is that the meaning of a complex 
statement can be somehow composed from the meanings of its parts. 
(Thats what people often call the principle of compositionality, and 
it applies to things like diagrams and maps as well as text.)

> The simplest case of this that I can think of is the
>concept 'give' ... {John gave candy to Mary} .... I have coded this in
>tripels for you amusement [1].  It is just this kind of conceptual
>dependency (as Shank called it) that triples do well.

I dont see that triples do it particularly *well*. They can do it, 
but so can almost anything that can encode directed graphs.

> And I agree, we need
>a concept (like 'slot' see diagram) to implement this above the RDF triples.
>
>[1] http://robustai.net/mentography/conceptualDependency.gif
>
>Incidentally, I'm still trying to wrap my pee brain around the idea that
>there is a problem with 'not' here.   To me {B subClass A.  C subClass A.  B
>not C.} is a perfectly valid thing to say and nicely implies {B xor C}.
>Does it not ?

Not sure what problem you mean. My point was only that anything above 
a simple ground atom would need some kind of syntax. Theres nothing 
particularly difficult about negation as such.

Pat

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Received on Friday, 18 May 2001 17:29:06 UTC

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