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[Frama-c-discuss] unproven VC with newer why version

Am 08.12.2009 um 14:54 schrieb Claude Marche:


>> 
> add "loop variant n-i;" and you should be done !

I had a look at section "loop variants" (page 37) in http://frama-c.cea.fr/download/acsl-implementation-Beryllium-20090902.pdf .
It says

	Optionally, a loop annotation may include a loop variant of the form
	...
	where m is a term of type integer .
	The semantics is as follows: for each loop iteration that terminates normally or with continue, the value of m at end of the iteration must be smaller 
	that its value at the beginning of the iteration. Moreover, its value at the beginning must be nonnegative. Note that the value of m at loop exit might be negative. 
	It does not compromise termination of the loop. 

It would be nice if this section would be more explicit that in general loop variants are necessary for (automatic?) provers because ...

Regards

Jens
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