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Re: [ontolog-forum] CL, CG, IKL and the relationship between symbols in

To: "John Black" <JohnBlack@xxxxxxxxxxx>
Cc: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Mon, 24 Dec 2007 13:18:58 -0800
Message-id: <p06230904c395cfab1f41@[]>
>Please forgive me, in advance, for my spotty knowledge of some of the topics
>in this post. My interest in these ideas often exceeds my understanding.
>First, congratulations to all on the ISO adoption of CL as a standard. I
>believe it will prove to be an invaluable addition to the spread of
>interoperable knowledge representation technology. It is an important
>achievement. I am doubly excited by this because it includes, at long last,
>an ISO standard for Conceptual Graphs. CGs was the first knowledge
>representation formalism I encountered. I read the CG1984 book several
>times, worked on an implementation in prolog of a linear form, and then had
>the pleasure to participate for a short time in 1997 on work towards the
>CGIF standard specification. More recently, having decided that semantics is
>heavily dependent on contexts, and searching for material concerning that
>subject, I came across IKL and the startling claim that "Every occurrence of
>an IKL name has the same meaning." This is something I find highly
>desirable, but which as I said, I had just recently decided was not
>possible.    (01)

I think you may be reading more into this than 
was intended. It does not say that every 
occurrence of an IKL name has the same unique 
referent in the actual world. It says that every 
such name occurrence maps to referents in all 
interpretations in the same way. But there may be 
many possible interpretations: there almost 
always are.    (02)

>The topic I am particularly interested in discussing here now, is this claim
>and a similar statement in the CL requirements section 5.1.4.b., "Any piece
>of Common Logic text should have the same meaning, and support the same
>entailments everywhere on the network. Every name should have the same
>logical meaning at every node of the network."    (03)

Right. Note, *logical* meaning. One might 
reasonably say that the meaning of "Patrick J 
Hayes" is me, in this particular world, but that 
is not its logical meaning. Its logical meaning 
is a mapping from interpretations (aka possible 
worlds) to an individual in that interpretation's 
universe.    (04)

>  Yet in the version of the
>Common Logic (CL) specification I have, in section 1 I read "The following
>are outside the scope of this standard: ... Computer-based operational
>methods of providing relationships between symbols in the logical 'universe
>of discourse' and individuals in the 'real world'".    (05)

Right.    (06)

>This topic, the operational relationship between symbols in logic and
>individuals in the world, happens to be my particular interest of late.
>Actually, come to think of it, I have been interested in this for some time    (07)

Join the club :-)  Seriously, this is a very 
large and interesting topic. One has to 
recognize, however, that it goes beyond the scope 
of logic as usually construed: certainly beyond 
the scope of Tarskian logical semantics.    (08)

>and I recall that one of the many things that impressed me about John Sowa's
>first book on Conceptual Structures in 1984 was the chapter on Psychological
>Evidence, including the discussion of perceptrons.    (09)

Perceptrons or perceptions? Perceptrons were a 
very early idea in what is now called neural 
networks.    (010)

>That section was, at
>least an initial attempt, to address the question.    (011)

? How does a perceptron (or a neural network more 
generally) address the question of how names come 
to be attached to their referents? I see no 
connection at all.    (012)

>So here is my first question: If the semantics of CL starts out with a
>mapping from the vocabulary of a CL text to individuals in the universe of
>discourse    (013)

Better say, in *a* universe of discourse. There 
is one universe for each interpretation, and 
there may be many equally correct interpretations.    (014)

>, but this mapping is nowhere encoded or included in the CL text    (015)

It cannot be encoded in text, being a mapping 
from text to what may well be non-textual things.    (016)

>then how can you be sure that one agents mapping to individuals at one node
>of the network will be the same as the mapping of another agent at some
>other node of the network?    (017)

You can't. The best you can do is to be sure that 
all the possible mappings that are consistent 
(using that word informally) with the conclusions 
that the second agent can draw, are also 
consistent with those that the originating agent 
can draw. That is a (rather convoluted) way of 
saying that they are both using the same logic 
and both respecting the notion of entailment that 
is supports. This is the best that any logical 
semantics can possibly guarantee.    (018)

Pat Hayes    (019)

>John Black
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