[gecode-users] Skipping branching alternatives?

[Guido Tack]

Am Montag, 10. Juli 2006 15:37 schrieb Luis Quesada:
> >Cutting off branches is normally considered part of exploration. [...]
>
> I don't agree with this bit Guido. Cutting off branching (i.e. pruning)
> is the very purpose of propagation. When you remove 5 from X's domain
> you are cutting off the branch associated with X=5.

Ok, maybe I wasn't clear enough. Typically, you specify your constraint 
problem using propagators and branchings, and this totally determines the 
shape of your search tree. Now, some sophisticated search engines prune the 
tree during search, e.g. B&B and SBDS. Of course, these engines post new 
constraints to do the actual pruning, which can be implemented as propagators 
or may just be basic tells.

Encoding a pruning of the tree into the initial model seems a bit weird - the 
model doesn't define a unique search tree any more.

Cheers,
	Guido

-- 
Guido Tack
Programming Systems Lab, Saarland University, Germany
http://www.ps.uni-sb.de/~tack