[gecode-users] Reifying constraints without posting them

[Christian Schulte]

Hi,

Did you try the nvalues constraint? It sounds that this will do the trick
for you.

You might then be able to minimize/maximize based on the integer variable
that nvalues uses for conting.

I have to admit that I do not really understand what you mean by pruning: if
you prune away solutions, this is just a bug in your model, isn't it?

Best
Christian

--
Christian Schulte, www.ict.kth.se/~cschulte/


> -----Original Message-----
> From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On
> Behalf Of Tommaso Urli
> Sent: Monday, April 29, 2013 9:10 PM
> To: 'gecode user list'
> Subject: [gecode-users] Reifying constraints without posting them
> 
> Hello,
>      I'm trying to introduce the following constraint in my model: let x
be a set of
> variables (an IntVarArray) and y a proper subset (a slice) of them, I want
to know
> how many variables in y get values among a given set of values. Problem
is: I
> want to implement this as a "soft"
> constraint, i.e. I want to minimize/maximize the number of times this
condition
> is satisfied, but without actually posting the constraint.
>      I have tried with reified membership constraints, but apart from
reification
> (that did exactly what I wanted it to do), they actually post propagators
and thus
> prune my search space. I have tried counting constraints as well, but none
of
> them matches the semantics I need, so I suspect that this kind of
constraint
> cannot simply be expressed, am I wrong?
> 
> Thanks,
> Tommaso
> 
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