[gecode-users] Re: Var indexes-help

[Guido Tack]

> Hi!
> (Sorry for so much questions on var indexes..)

No problem.

> I have an IntVar, say I, to specify an index of a VarArray and
> I want to post some constraints (like element, linear) for indexes  
> between 0(zero) and I.
>
> is there a way to express;
>
> if (current_index < I ) then element(....) + linear(....)
>
> And generally speaking, I cant see the way to tell the
> if___then___ structure.

You can model this using reified constraints and Boolean implication:

	BoolVar b0(this, 0, 1);
	BoolVar b1(this, 0, 1);
	rel(this, I, IRT_GR, current_index, b0);
	linear(...., b1);
	rel(this, b0, BOT_IMP, b1, 1);

However, there is no reified version of element, you'll have to  
express that in a different way.

Cheers,
	Guido