gabriele renzi wrote:
> 1) is it possible to express a constraint so that an FD.intvar is
> bound to
> be one of two choices which are themselves FD.intvar's ?
> I believe this should be done with FD.gcc4 but I'm not sure if this
> is the
> right thing.
Do you mean a constraint like (x = y) or (x = z)? That's not what
gcc is used for, but you can use reified constraints to achieve this:
val b1 = FD.boolvar space
val b2 = FD.boolvar space
val b3 = FD.intvar2boolvar(space, FD.intvar(space, #[(1,1)])) (* b3
= true *)
val _ = FD.disj(space, b1, b2, b3) (* b1 or b2 = b3 *)
val _ = FD.Reified.rel(space, x, FD.eq, y, b1) (* x == y <=>
b1 *)
val _ = FD.Reified.rel(space, x, FD.eq, z, b2) (* x == z <=>
b2 *)
> 2) about gcc*: what is the meaning of all the paramaters in the
> various FD.gcc ?
> [s,x,min,max,level] are clear from the description, but
> [v,c,m,ulow,uup,all] are not so obvious, in my humble opinion.
You're right, they are not obvious at all, and the documentation for
gcc practically doesn't exist. In fact, we realized that this
interface doesn't work as expected for some cases, and -
unfortunately - it's currently not a good idea to try to use it... I
hope it's not vital for the problem you're trying to model.
Cheers,
Guido
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