Hi Philippe,

I assume from what you write that you the variables of your problem(s) stay the 
same while the constraints change. Is tthat correct?

Then, what you can do is to take a space for the new problem (with the new 
constraints) and assign the variables in the new problem to the values of the 
old problem. If the space fails, the old solution is not any longer valid. The 
cost can be accessed as always...

Hope that helps
Christian

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

-----Original Message-----
From: users-boun...@gecode.org [mailto:users-boun...@gecode.org] On Behalf Of 
Philippe
Sent: Wednesday, October 16, 2013 12:09 AM
To: users@gecode.org
Subject: [gecode-users] Stability of a solution

Hi all,

I have a constraint satisfaction problem correctly solved by gecode using a 
Branch &  Bound engine. However, I have a stability issue : 
This problem should be solved frequently with minor changes and I get a 
different solution each time I solve it (I solve it from scratch  every 3 s and 
the search is time constrained to 10 ms)

Thus, to have a stable solution, I have to know if the previous solution  is 
still valid and I have to compare its cost (relatively the updated problem) to 
the best new solution. Unfortunately, this previous solution is not always  
analyzed (even if this solution is  probably still relevant) since I am time 
constrained.

Is there an elegant way to check if the previous solution is still valid and to 
 compute its cost?

Thanks for tips,
Cheers,
Philippe


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