[gecode-users] Reified Distinct Constraint

[Christian Schulte]

No, not really. I do not know what this distinct would be good for. A more
useful one would be a soft distinct where the number of violations is
counted (there, one actually also could get some propagation). Check for
example:
	http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.3.7071

What do you need a reified distinct for?

Christian

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


-----Original Message-----
From: Max [mailto:chaosangel at gmx.de] 
Sent: Tuesday, February 17, 2009 10:32 AM
To: Christian Schulte
Cc: 'gecode list'
Subject: Re: [gecode-users] Reified Distinct Constraint

Thank you for the quick answer.
Is this feature planned for the release of GeCode3.0?
I just found a mail in the archive of somebody requesting the same feature.
Currently i do use O(n^2) constraints for this, but i wanted to show 
that i can transform it into a constant number of rules.
Thats why i would need the reified version.

Max

Christian Schulte wrote:
> No, there is no reified version. The best you can do at emulating is use
> excessive reification: Create O(n^2) reified disequality constraints for
all
> variable-variable pairs, and then the reified control variable is the
> conjunction of all the control variables from the disequalities. As said,
> not very good.
>
> Christian
>
> --
> Christian Schulte, www.it.kth.se/~cschulte/
>
> -----Original Message-----
> From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
> Of Max Ostrowski
> Sent: Monday, February 16, 2009 2:21 PM
> To: gecode list
> Subject: [gecode-users] Reified Distinct Constraint
>
> I just found the distinct constraint, that hopefully makes all variables
> distinct. This could greatly reduce the number of constraints, as i am
> translating from a logic program.
> But i would need a reified version of the distinct constraint.
> I there any or can i at least emulate thie behaviour?
>
> Thank you in advance,
> Max
>