[Gecode] Batch recomputation in standard search engines

[Guido Tack]

Hi!

After spending some time trying to find out why the test cases I wrote 
for my propagators didn't work, I'd like to share my experience with you ;-)

I am using randomized branchings to generate test cases for the set 
propagators. The problem with randomized branchings is that you have to 
make them deterministic in order to behave well during backtracking. 
Batch recomputation is just perfect for that, you ask the space only 
once for a description that contains the (randomized) choice at this 
point. Then you use the very same description to commit to the left and 
the right branch. Unfortunately, the current search engines do not 
compute the description only once, but once for the left branch and once 
for the right branch. This of course completely screwed my randomization.

Is there any argument against using one description for both branches? 
If not, I'd like to change the search engines such that they become 
deterministic in the sense described above.

Cheers,
    Guido