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Re: working on "A Model of Authority in the Web"

From: Dan Connolly <connolly@w3.org>
Date: Tue, 22 Dec 2009 07:37:18 -0600
To: jos.deroo@agfa.com
Cc: public-cwm-talk <public-cwm-talk@w3.org>
Message-ID: <1261489038.5304.12962.camel@pav.lan>
On Mon, 2009-12-21 at 21:43 +0100, jos.deroo@agfa.com wrote:
> Dan Connolly wrote: 
> [...]
> > It's not sound to go from
> >   Exists x. P(x) -> Q(x)
> >   P(a)
> > to
> >   Q(a)
> 
> That is indeed unsound but there is no such rule 
> with an Exists x where x occurs in the conclusion. 

It's unsound even if x doesn't occur in the conclusion.
Consider an example: is it sound to go from:

  There is one professor who, if he likes your work,
  you can get into the school.

  Professor Bob likes your work.

to

  You can get into the school.

?


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
gpg D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Tuesday, 22 December 2009 13:37:21 UTC

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