--- layout: fc_discuss_archives title: Message 50 from Frama-C-discuss on December 2009 ---
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[Frama-c-discuss] Lemma from ACSL doc doesn't verify



Hollas Boris (CR/AEY1) wrote:
> If I use
>
> /@ lemma mean_property2: \forall integer l, h; l <= h  ==>  l <= (l+h)/2 <= h;
>
> Instead of the lemma above and try to use it for numbers of type int, will the prover detect that mean_property2 doesn't hold for int as (l+h) may overflow?
>
>   
Lemma mean_property2 DOES HOLD for int since in annotations, + means 
addition on integers and not on ints.

- Claude

PS: If for some weird reason you want to use addition of ints in logic 
you can add a cast: (int)(l+h), but in general there is no reason to do 
that.


> -Boris
>
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-- 
Claude March?                          | tel: +33 1 72 92 59 69           
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