[gecode-users] Combining of LDSB with Branch and Bound algorithm.

[Chris Mears]

Hello,

> Hi,I have two questions please:
> 1- I want to know the theoretical principle of LDSB for symmetry
>  breaking. 

The principle and inner workings of LDSB are described in this paper:

Lightweight dynamic symmetry breaking.
Christopher Mears, Maria Garcia de la Banda, Bart Demoen, Mark Wallace.
Constraints 19(3), pp. 195-242. 2014.

You can get a copy from Springer
(http://link.springer.com/article/10.1007/s10601-013-9154-2)
or from here (http://www.cmears.id.au/files/papers/2013-LDSB.pdf).

> 2- if in an algorithm i would combine a branch and bound  algorithm
> with the use of the LDSB layer for symmetry reduction ( declaration
> of symmetries), so how the solver (algorithm) works ? Can someone
> explain to me the sequential steps of the execution of the set
> (Branch and bound, LDSB).

For LDSB there's no difference between DFS and branch-and-bound.  LDSB
adds some extra constraints at certain choice points; it doesn't
interact directly with the solver engine (DFS/BAB).  In the Gecode
sense, it's just a special kind of Brancher.