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# [Frama-c-discuss] Floor problem

```Hi Sebastian,

Proving your assertions from the axioms you gave requires an induction.
Automated provers cannot do that. Here is a better definition. The four
lemmas are proved by Z3

/*@ axiomatic Floor {
@   logic integer floor(real a);
@   axiom floor: \forall real a; floor(a) <= a <= floor(a)+1;
@ }
@*/

//@ lemma floor01: floor(0.1) == 0;
//@ lemma floor105: floor(10.5) == 10;
//@ lemma floorm01: floor(-0.1) == -1;
//@ lemma floorm105: floor(-10.5) == -11;

- Claude

Le 18/11/2014 10:00, Sebastian a ?crit :
> Hi,
> I tried to use \floor but it raised an error:
> "The full backtrace is:
> Raised at file "hashtbl.ml", line 353, characters 18-27
> Called from file "hashtbl.ml", line 361, characters 22-38
> Plug-in wp aborted: internal error.
> Reverting to previous state.
> Look at the console for additional information (if any).
> Please report as 'crash' at http://bts.frama-c.com/.
> Your Frama-C version is Neon-20140301.
> Note that a version and a backtrace alone often do not contain enough
> information to understand the bug. Guidelines for reporting bugs are at:
> http://bts.frama-c.com/dokuwiki/doku.php?id=mantis:frama-c:bug_reporting_guidelines";
>
>
> So I tried to implement an axiomatic floor function.
> I am using "Frama-C Neon-20140301" with Alt-Ergo prover on Ubuntu 14.04.
> I have tried to test it with a simple example but my axiomatic floor
> doesn't work and I am not able to find the error.
> I have made a "testFloor" function with
> assert clauses, but the prover was not able to prove it.
> I attached the axiomatic Floor definition and the "testFloor" function.
> Could anyone please suggest how I can proceed with finding a solution to
> this problem?
>
> Thank you very much,
> Sebastian
>
>
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