--- layout: fc_discuss_archives title: Message 84 from Frama-C-discuss on December 2009 ---
Hollas Boris (CR/AEY1) wrote: >> Would it be useful to add automatically a clause "variant N-i;" for >> loops having the simple syntactic structure "for (i = ... ; i < N ; >> i++)"? This way proof obligations for such loops (which are quite >> common) would be automatically discharged. >> > > >> Regards, >> david >> > > In C, the loop variable can be modified in the body. Hence, The loop variant you propose may not hold. If a variant was added automatically, it wouldn't be possible to verify these loops. The same is true for loop invariants. > Yes, that's why I'm reluctant to implement such an heuristic. the same for the heuristic loop inv 0 <= i <= N But I think it would be possible to implement another plugin devoted to suggest simple annotations like this. Then running Jessie on the automatically annotated code could be done, and do a manual modification for wrong generated annotations. In other words, I don't think it is a good idea to generate such an annotation without telling the user. - Claude > A solution is to use abstract interpretation to infer simple loop invariants and variants automatically. > > _______________________________________________ > Frama-c-discuss mailing list > Frama-c-discuss at lists.gforge.inria.fr > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/frama-c-discuss > -- Claude March? | tel: +33 1 72 92 59 69 INRIA Saclay - ?le-de-France | mobile: +33 6 33 14 57 93 Parc Orsay Universit? | fax: +33 1 74 85 42 29 4, rue Jacques Monod - B?timent N | http://www.lri.fr/~marche/ F-91893 ORSAY Cedex |