[gecode-users] algorithm used in sequence constraint

[David Rijsman]

Hi Kish,

IntSet can only take values 0 and 1 otherwise a NotZeroOne exception will be thrown (actually undocumented I see now) . If both values are in IntSet nothing needs to be done if l equals 0 and u is greater or equal to q, if this is not the case the constraint can not be true. I don't map the more integer version onto 1 (boolean version)  but the boolean version on the integer version, basically one implementation independent of (bool or integer) view and type of variable. 

hope this helps,

David

>>> 
From: 	Kish Shen <kisshen at cisco.com>
To:	David Rijsman <David.Rijsman at quintiq.com>
CC:	<users at gecode.org>
Date: 	8/19/2010 3:21 PM
Subject: 	Re: [gecode-users] algorithm used in sequence constraint

David Rijsman wrote:
> Hi Kish,
> 
> it is indeed possible to remove the IntSet s argument in the sequence constraint for boolean variables but we choose to explicitly state what value we are counting and use the IntSet for the following reason, I quote from Christian:
> 
> "we never use the C++ type bool for Boolean values as Boolean variables also take integer values. And also  choosing a set makes it easier to interface and just forget about the fact whether one is using IntVar or BoolVar."
> 
> David
> 
Hi David,

So I assume the IntSet s can only take the values 0 and 1 for the 
BoolVar case, and is really only useful if it has either 1 or 0 only? 
[If it has both 0 and 1, then all variables must take those values]

In the ECLiPSe version, there seems to be a more fundamental reason why 
the 0/1 (ECLiPSe 'boolean' version) version counts 1 -- the algorithm is 
implemented using this version, i.e. the more general version is 
actually mapped onto the 0/1 version. Is this also the case in your 
version?

Thanks and cheers,

Kish
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