Frama-C-discuss mailing list archives

This page gathers the archives of the old Frama-C-discuss archives, that was hosted by Inria's gforge before its demise at the end of 2020. To search for mails newer than September 2020, please visit the page of the new mailing list on Renater.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Frama-c-discuss] Small function with Shifting

  • Subject: [Frama-c-discuss] Small function with Shifting
  • From: Claude.Marche at (Claude Marche)
  • Date: Thu, 20 May 2010 17:05:19 +0200
  • In-reply-to: <1274363209.2116.19.camel@iti27>
  • References: <> <> <1274361797.2116.11.camel@iti27> <20100520153057.1f967bce@is010235> <1274363209.2116.19.camel@iti27>

Boris Hollas wrote:
> On Thu, 2010-05-20 at 15:30 +0200, Virgile Prevosto wrote:
>> No, jessie always generates a proof obligation corresponding to the
>> lemma. However, no automated prover will be able to discharge it
>> (otherwise, they would prove the PO from the ensures clause directly).
>> Thus, some additional work is needed (e.g. by using the coq output of
>> why).
> I don't understand that why no automatic prover will be able to prove a
> user-supplied lemma. Isn't this what SMT provers are supposed to do?
> I thought that a lemma is a way to reduce the search space for the
> prover by giving it a hint on how to prove the postcondition.
Indeed, you are right and Virgile is not: It is possible that a prover 
proves both the lemma
and the assertion which need that lemma, but does not prove the 
assertion without the lemma.
So yes, a lemma may act as an hint.

- Claude

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      |
F-91893 ORSAY Cedex                    |