[gecode-users] Reified Distinct Constraint

[Christian Schulte]

Yep, that's why I wrote "would be". Just wishful thinking and trying to make
the point that if I'd the time, I'd put it into a soft distinct rather than
a reified one.

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, March 02, 2009 11:06 AM
To: users at gecode.org
Subject: Re: [gecode-users] Reified Distinct Constraint

Hmm, maybe i got you wrong, but i did not found a "soft_distinct" function
in the gecode library.

Max
-------- Original-Nachricht --------
> Datum: Mon, 2 Mar 2009 15:01:08 +1100
> Von: Malcolm Ryan <malcolmr at cse.unsw.edu.au>
> An: gecode list <users at gecode.org>
> Betreff: Re: [gecode-users] Reified Distinct Constraint

> Well a 'soft distinct' like this could easily be converted to a  
> reified distinct:
> 
> soft_distinct(args, nViolations);
> BoolVar b = post(space, ~(nViolations == 0));
> 
> Malcolm
> 
> On 17/02/2009, at 8:36 PM, Christian Schulte wrote:
> 
> > 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
> >>
> >
> >
> >
> > _______________________________________________
> > Gecode users mailing list
> > users at gecode.org
> > https://www.gecode.org/mailman/listinfo/gecode-users
> 
> 
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