Re: constraints...

[Ludovic Langevine]

According to the beta version of the FD tracer, Q #= 10*A*(10*B + C) 
creates the constraint:
ax_plus_by_eq_z(100, var(4), 10, var(5), var(6))
( 100 * I + 10 * J #= K where I, J, K are intermediate variables in 
[0..268435455] )
and this constraint fails before making any domain reduction.

Source code of the constraint:

ax_plus_by_eq_z(int A,fdv X,int B,fdv Y,fdv Z)
{
 start X in (min(Z) - B*max(Y)) /> A .. (max(Z) - B*min(Y)) /< A
 start Y in (min(Z) - A*max(X)) /> B .. (max(Z) - A*min(X)) /< B
 start Z in A*min(X) + B*min(Y) .. A*max(X) + B*max(Y)
}

your example does not work for A = 100 and B in [9,15]... [2^3+1, 2^4-1] 
: maybe an arithmetic overflow?

This 'by hand' splitting works:
fd_domain([A,B,C], 1, 9), A10 #= 10*A, B10#=10*B, D #= A10*B10, Q #= D + 
A10 * C.
but this is not very satisfactory!


PRADOS Julien wrote:
> yes it looks like a bug...
> in gprolog v 1.2.16
>
> this predicate succeed
> fd_domain([A,B,C],1,9), Q #= 8*A*(10*B + C).
>
> and this one fail !!!
> fd_domain([A,B,C],1,9), Q #= 10*A*(10*B + C).
>
> why ???
>
>
>
>
> fred bapst wrote:
>
> > The constraints (A#=10*B+C) should be identical to
> > (Z#=10*B, A#=Z+C), no ? (Ok, I'm aware of differences
> > in  the propagation and of overflow risk...).
> >
> > Does anybody know why the following fraction0 fails
> > whereas fractions1 succeeds (with gnu prolog 1.2.8) ?
> >
> > Thanks in advance.
> >
> > -----------------------------------------------
> >
> > fractions0(Ls) :-
> >        Ls = [A,B,C,D,E,F,G,H,I],
> >        fd_domain(Ls, 1, 9),
> >        fd_all_different(Ls),
> >        A*(10*E+F)*(10*H+I) + D*(10*B+C)*(10*H+I) +
> > G*(10*B+C)*(10*E+F) #= (10*B+C)*(10*E+F)*(10*H+I),
> >        fd_labelingff(Ls).
> >
> > fractions1(Ls) :-
> >        Ls = [A,B,C,D,E,F,G,H,I],
> >        fd_domain(Ls, 1, 9),
> >        fd_all_different(Ls),
> >        BC #= 10*B+C, EF #= 10*E+F, HI #= 10*H+I,
> >        A*EF*HI + D*BC*HI + G*BC*EF #= BC*EF*HI,
> >        fd_labelingff(Ls).
> >
> >
> > ___________________________________________________________
> > Do You Yahoo!? -- Une adresse @yahoo.fr gratuite et en français !
> > Yahoo! Mail : http://fr.mail.yahoo.com
> >
> >
> > _______________________________________________
> > Users-prolog mailing list
> > address@hidden
> > http://mail.gnu.org/mailman/listinfo/users-prolog
> >
> >  
>
>
>
>
>
>
> _______________________________________________
> Users-prolog mailing list
> address@hidden
> http://mail.gnu.org/mailman/listinfo/users-prolog