[gecode-users] branching and copy in Gecode

[Guido Tack]

Hi,

backtracking always jumps back to a copy and then recomputes the node that it actually wants to jump to.  So you can maintain your propagator data structures incrementally, as long as they're copied (or marked for recomputation) during cloning.  See chapter 7.2 in MPG for a more detailed explanation of recomputation.

Cheers,
Guido

On 28/10/2012, at 2:23 , Jun He <hejunnudt at gmail.com> wrote:

> Hi,
> 
> In Gecode, copy doesn't happen for every branching of the search tree, and whenever a failure happens it just backtracks to a node between the current failure node and the previous copied node.  If a propagator works dependent on some data structure, and the backtrack jumps to a node that is not copied, then the data structure should be recomputed.  My question is how to maintain the data structure incrementally for the propagator?  Is there an easy setting to make Gecode copy at each branching, so that a simple undo policy can be used to maintain the data structure?
> 
> Best regards,
> Jun
> 
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-- 
Guido Tack,
http://www.csse.monash.edu/~guidot/



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