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Re: Intensional intersection means what?

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 20 Jun 2001 14:45:29 +0100
To: "Roger L. Costello" <costello@mitre.org>
Cc: xmlschema-dev@w3.org
Message-ID: <f5bsngv8dty.fsf@cogsci.ed.ac.uk>
"Roger L. Costello" <costello@mitre.org> writes:

> The structure's spec repeatedly uses the following phrases:
>    - intensional intersection
>    - intensional union
>    - intensional subset
> but does not define them.

Sure it does, as you quote below -- "as defined in Attribute Wildcard
Intersection", which in turn says "For a wildcard's {namespace
constraint} value to be the intensional intersection of two other such
values . . .", which is a definition of 'intensional intersection'.

> Can someone tell me what they mean?


> What if the above had just said ".. is the intersection of the ...". 
> Would this sentence mean anything different?  

Sure -- it would be incoherent -- intersection as such is an operation 
on sets.  A wildcard definition isn't a set, it's a characteristic
function for a (possibly infinite) set.  By 'intensional' I mean that
the operation is defined at the characteristic function == descriptive 
level, not the set level itself.

  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
Received on Wednesday, 20 June 2001 09:45:29 UTC

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