[gecode-users] Critical bug.

[Rafael Meneses]

Hi,

The problem is in ViewValBranching:

1.- The status method calculate the "start" variable.

2.- The description method create the branch description, with the
position and value of the variable to make the branch. _The position
is absolute_.

3.- The commit, impose the branch description, since the position is
absolute, _position is position minus offset_ , but the offset depends
of the start variable, but status method in the recomputation phase is
not called, so the start variable is  zero. This produces that the
offset is distinct between the original node and the recompute one,
then the branch is made in other variables and not in the original
one.

Options to repair the problem are:
* pass the start variable to the branching description
* don't make processing in the status method
* ...

I think that the error is critical, because produce that the
recomputation fix other variables, and we lost sector of the search
space.

I attach a patch that implement the first option.

I detected the problem, when my code crashed extraneously... two days
of hard work :(


Saludos,

-- 
Rafael Meneses
http://www.zeke.cl
http://www.labsd.inf.utfsm.cl/~rmeneses
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