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Re: question about imports

From: pat hayes <phayes@ai.uwf.edu>
Date: Thu, 5 Dec 2002 19:28:41 -0600
Message-Id: <p05111b13ba15abe02674@[10.0.100.86]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-webont-wg@w3.org

>From: pat hayes <phayes@ai.uwf.edu>
>Subject: Re: question about imports
>Date: Thu, 5 Dec 2002 16:54:24 -0600
>
>>  >From: pat hayes <phayes@ai.uwf.edu>
>>  >Subject: question about imports
>>  >Date: Thu, 5 Dec 2002 12:27:45 -0600
>>  >
>>  >>
>>  >>  As I understand things, the current meaning of imports is that including
>>  >>
>>  >>  owl:imports B
>>  >>
>>  >>  in a document A has exactly the same meaning as copying the imports
>>  >>  closure of B into A.
>>  >>
>>  >>  So I have a question: consider two documents A and AC which are
>>  >>  identical except that A contains owl:imports B, and AC actually has
>>  >>  the imports closure of B copied into it at that point, but has no
>>  >>  reference whatever to B.
>>  >
>>  >This is different from the previous proposal in that it drops the imports
>>  >triple.
>>  >
>>  >>  These two documents have exactly the same
>>  >>  meaning, right?
>>  >
>>  >No, because the second is missing a triple.
>>
>>  They are syntactically distinct, but I believe they are true in
>>  exactly the same interpretations (?). Keeping the imports triple with
>>  the imported graph is like saying P and P instead of P, right?
>
>Huh?  Are you thinking that this is a dark triple?

No, of course not. But the truth-conditions on owl:imports B are 
exactly the same as the truth conditions on the imports closure of B, 
right (??) If not, what *are* the truth conditions on owl:imports?

>  When did these come back?
>
>>  >>  And the first, but not the second, refers to another
>>  >>  document.
>>  >
>>  >And they have different meaning (as n-triples documents).
>>  >
>>
>>  In what does the difference reside?
>
>I thought that every triple made an assertion.

I never said otherwise. That is beside the point of my question. What 
assertion does the imports triple  (considered in isolation, a single 
triple) actually make, other than that imports closure be true? (And 
BTW, what is the subject of that triple, and how does it enter into 
the truth-conditions?)

>If this is no longer true,
>then I'm going to have a pile of changes to make.

Not only is it true, one can say more: it asserts that the <s,o> pair 
is in the extension of the property. What are the semantic conditions 
on IEXT(I(owl:imports)) ?

Pat

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Received on Thursday, 5 December 2002 20:28:46 GMT

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