[gecode-users] Display the values of a set of variable without duplicates

[Guido Tack]

I guess the problem is that you only want to see x,y but you need to search on z,k first? That's a bit more tricky.
You can use a restart search engine, which restarts after each solution. Then for each solution you add the negation of the solution as a constraint in the root, e.g. (not (x==1 and y==1)). I'm not sure how well this scales if you have many solutions, but it could be worth a try.

Cheers,
Guido

On 31/05/2013, at 12:04, Christian Schulte <cschulte at kth.se> wrote:

> Hi,
> 
> I am not sure whether I understand your question correctly. But you can
> exchange the order of the search engine (that is, in my previous reply swap
> e1 and e2).
> 
> Best
> Christian
> 
> --
> Christian Schulte, Professor of Computer Science, KTH,
> www.ict.kth.se/~cschulte/
> 
> 
> -----Original Message-----
> From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
> Of Amina Kemmar
> Sent: Friday, May 31, 2013 10:00 AM
> To: users at gecode.org
> Subject: [gecode-users] Display the values of a set of variable without
> duplicates
> 
> Hello,
> 
> I already asked for the following problem:
> 
> According to the variables defined in our model (x,y,z,k), I obtained the
> following solutions :
>  1,1,2,3
>  1,1,5,6
>  1,1,7,9
>  1.1,8,8
> I am interested to the values of the two variable x and y, so I want to
> avoid the enumeration of the three last solution in order to display just
> the first solution.
> 
> I got the following response:
> 
> One way to do it is as follows:
>  - You create a space s that only has a brancher for x and y
>  - You create a search engine e1 for s and find a solution, say s1
>  - You post a brancher in s1 for z and k.
>  - You create a search engine e2 for s and find just a single solution!
>  - You can then also get more solutions from e1 and repeat the previous two
> steps.
> 
> Thank you for the solution, it works very well, but I have an other problem
> which is the enumeration order of the variables x, y, z and k. I must begin
> the branching from the variables  z and k, then x, y (In this way, Gecode
> enumerates quickly the solutions but for the first order "x,y,z,k", it takes
> about 30 minutes to enumerate the first solution).
> Is there an other solution?
> 
> Thank you.
> -----
> Amina
> 
> 
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