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Re: [ontolog-forum] OpenCyc OWL Files

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "John F. Sowa" <sowa@xxxxxxxxxxx>
Date: Thu, 26 Feb 2009 00:46:25 -0500
Message-id: <49A62CB1.8090908@xxxxxxxxxxx>
Chris,    (01)

JFS>> ...The old KIF 3.0 had a backquote, which I used to
 >> support contexts in conceptual graphs (which were influenced
 >> by Peirce's contexts, which have similar expressive power
 >> to McCarthy's contexts).  I was very happy to get the 'that'
 >> operator in IKL, which can be used in the same way as backquote.    (02)

CM> It is semantically superior to backquote, however, especially
 > for representing intensional contexts.  Intuitively, what we
 > believe, fear, desire, etc are propositions (or states of affairs,
 > etc -- whatever structured entity you take that-clauses to denote),
 > not sentences.    (03)

I agree that the 'that' operator is more appropriate for propositions
than the KIF backquote.  Since the concepts in conceptual graphs
have a type label, I introduced a kind of "type coercion" in my
original 1984 book.    (04)

For example, consider the conceptual graph for the sentence
"The cat Yojo is on a mat."  In CGIF, it would be represented,    (05)

    [Cat: Yojo] [Mat *x] (On Yojo ?x)    (06)

Or in the older linear notation, which is slightly more readable,    (07)

    [Cat: Yojo]->(On)->[Mat]    (08)

If I want to refer to that graph as a graph, I can write    (09)

    [Graph: [Cat: Yojo]->(On)->[Mat]]    (010)

But I might want to refer to the proposition whose statement (Stmt)
is that graph:    (011)

    [Proposition]->(Stmt)->[Graph: [Cat: Yojo]->(On)->[Mat]]    (012)

By the convention of type coercion, a graph nested inside a concept
of type Proposition is used to state the proposition.  Therefore,
the above graph can be abbreviated as    (013)

    [Proposition: [Cat: Yojo]->(On)->[Mat]]    (014)

The following graph represents a situation described (Dscr)
by a proposition stated by the nested graph:    (015)

    [Situation]->(Dscr)->[Proposition: [Cat: Yojo]->(On)->[Mat]]    (016)

And by a second application of type coercion, this graph could
be abbreviated as    (017)

    [Situation: Yojo]->(On)->[Mat]]    (018)

In translating CGs to KIF 3.0, I mapped the concepts of type Graph
to a KIF expression that used backquote.  The concepts of type
Proposition and Situation used type coercion.    (019)

John    (020)

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