[gecode-users] Fwd: Re: propagation consistency of count (single value) constraint

[Kish Shen]

I think I didn't send this to the mailing list, so here it is...

-------- Forwarded Message --------
Subject: Re: [gecode-users] propagation consistency of count (single 
value) constraint
To: cschulte at kth.se
References: <55DE1FB2.90108 at cisco.com> <55DF3132.8080407 at cisco.com> 
<00ba01d0e4a5$32dd8720$98989560$@kth.se>
From: Kish Shen <kisshen at cisco.com>
Message-ID: <55EBC8B7.3020207 at cisco.com>
Date: Sun, 6 Sep 2015 06:01:43 +0100
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On 01/09/2015 11:58, Christian Schulte wrote:
> Hmm, I had a quick look at the code and I think it should rewrite to the
> int/int case. I am travelling right now, so I will look more carefully when
> I am back in a week or so.
>

Hi Christian,

I looked at the program more closely, and it seems that the reason for
the apparent better performance with ICL_BND is because the constraint
succeeds when it is violated. The following does not fail when posted
with ICL_BND:

count(home, x, y, IRT_GR, z, ICL_BND)

x = {5,5,5,5,5,5,5}, y = 1, z = 0

y and z are IntVars with singleton domains.

This succeeds when posted with x set to all 5s, or as variables which
are then labelled to 5 during the search.

The constraint fails when posted with ICL_DOM.

Cheers,

Kish