[gecode-users] LDSB : symmetries on value tuples and depending symmetries

[Martin Mann]

Hi,

me again on LDSB.

I played around with LDSB for my problem on two sets of variables X1 and 
X2 that have different domains and symmetries. X1 and X2 are coupled by 
some strong user defined constraints, so not independent.

Actually, my situation is like that:

I have a symmetry function "s" that can generate for each solution "a" 
the set of symmetric assignments on X1 and on X2 (independently). The 
problem is defined in a way that all symmetries from X1 are 
theoretically combineable with symmetric assignments on X2.

Thus I would like to do something like that:

- for each assignment a1 on X1
  + find assignment a2 on X2
  + ensure during remaining search implication
    if(a1) --> [X2 not s(a2)] for all symmetries of a2
  + ensure during remaining search
    [X1 not s(a1)] for all symmetries of a1
  + continue search

So I am basically looking for a symmetry breaking for value tuples since 
I am not sure if simple value symmetry breaking is really doing the job 
(at least my first tests dont give me the feeling).

Is there a possibility with LDSB or do you see some way to build such a 
framework? I did something similar years back for Gecode 1, but not sure 
if I want to reengineer my own code.. ;)

Thanks for any hints,
Martin


-- 
Dr. Martin Mann, Postdoc
Bioinformatics - Inst. of Computer Science
Albert-Ludwigs-University Freiburg
Tel: ++49-761-203-8254
Fax: ++49-761-203-7462
http://www.bioinf.uni-freiburg.de/~mmann/