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[Frama-c-discuss] problems with recognition of the variant

  • Subject: [Frama-c-discuss] problems with recognition of the variant
  • From: bagnara at cs.unipr.it (Roberto Bagnara)
  • Date: Fri, 12 Dec 2014 08:22:22 +0100
  • In-reply-to: <CAAEWojUFkWjLv9yDjp37=zP0coN1xnFxuuhNc0ER_570HpFpYQ@mail.gmail.com>
  • References: <CAAEWojUFkWjLv9yDjp37=zP0coN1xnFxuuhNc0ER_570HpFpYQ@mail.gmail.com>
On 20/11/2014 18:03, ALESSIO BORTOLOTTI wrote:
> While I was trying to prove a while loop containing shifts, I ran into a problem: the program couldn't recognize the variable on which I have done the shift as a variant.

I stumbled upon the same issue.  Apparently the latest version
of Frama-C is not able to prove that a nonzero unsigned quantity
shifted to the right by a nonzero number of positions results
in a strict decrease.  Replacing shift by integer division does
not help.  Can someone on this list explain what is going on?
Is there a workaround for this problem?
Kind regards,

    Roberto

-- 
     Prof. Roberto Bagnara

Applied Formal Methods Laboratory - University of Parma, Italy
mailto:bagnara at cs.unipr.it
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