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RE: ISSUE 15.24 if or iff - current state - propose to close

From: Smith, Michael K <michael.smith@eds.com>
Date: Mon, 18 Nov 2002 18:00:11 -0600
Message-ID: <B8E84F4D9F65D411803500508BE3221411F92C10@USPLM207>
To: Jeremy Carroll <jjc@hpl.hp.com>, www-webont-wg@w3.org

Thanks Jeremy.  My face is red.  No wonder it seemed odd.

-----Original Message-----
From: Jeremy Carroll [mailto:jjc@hpl.hp.com]
Sent: Monday, November 18, 2002 1:54 PM
To: www-webont-wg@w3.org
Subject: RE: ISSUE 15.24 if or iff - current state - propose to close

Mike Smith said:
>Under the IFF interpretation, the following holds

> P rdfs:range A
> P rdfs:range B
> ->
> A = B

No, that's not it - and probably explains why you're seeing it differently.

The iff is not saying that

<
if

P rdfs:range A

then that
[
x P y   

iff y in A
]
>

but

<
P rdfs:range A
if and only if
[
if
x P Y
then
y in A
]
>

So for instance, for any empty property P and any class A we have
[
if
x P y
then
y in A
]
trivially
and so P rdfs:range A.

Jeremy
 
Received on Monday, 18 November 2002 19:00:27 GMT

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