Re: Constraint solver generates invalid solutions

[Daniel Diaz]

Hi Markus,

sorry for the bug ... and for the late reply !
The bug is fixed in 1.4.2 which will be released in few days.

Here is a snapshot:
http://gprolog.univ-paris1.fr/unstable/gprolog-20121122.tgz

BTW: I attach a simple prolog file which performs the same test as yours 
but in a single file and then much faster.
I could test with N=14 (needs more than 1 day on my machine).

Daniel


Le 28/10/2012 13:26, Markus Triska a écrit :
> Hi Daniel,
>
> Daniel Diaz <address@hidden> writes:
>
> >    DATE++;
> >    if (DATE < 0)
> >       DATE = 1;
> I noticed you included this change in GNU Prolog 1.4.1. I have now
> constructed a simpler test case which shows that this does not fix the
> problem. GNU Prolog 1.4.1 still emits wrong answers within 5 days on an
> iMac (2.66 GHz) with the following test case, which uses only a single
> fd_all_different/1 constraint:
>
>     run :-
>             L = 20,
>             length(Ls, L),
>             fd_domain(Ls, 1, L),
>             fd_all_different(Ls),
>             fd_labeling(Ls),
>             portray_clause(Ls),
>             false.
>
> I'm attaching two files that let you reproduce the problem:
>
>     alldif.pl: Posts fd_all_different/1, labels and emits all solutions
>
>     alldif_verify.pl: Reads solutions from stdin and verifies them
>
> Just compile them as usual with "gplc alldif.pl" and "gplc
> alldif_verify", and then use them together with:
>
>     $ ./alldif | ./alldif_verify
>
> alldif_verify emits a line every 10.000th solution. The first few
> million solutions are all valid:
>
>     0.
>     1.
>     2.
>     3.
>     ....
>
> but after about 5 days, GNU Prolog 1.4.1 emits an answer that does not
> satisfy the fd_all_different/1 constraint:
>
>     ...
>     124964.
>     124965.
>     false - [1, 2, 3, 4, 5, 6, 7, 10, 16, 12, 14, 8, 18, 11, 20, 17, 19, 13, 9, 
> 13].
>
> Please let me know if you need any further information.
>
> Thank you and all the best,
> Markus


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alldiff.pl
Description: Perl program