[gecode-users] Random Behavior

[Guido Tack]

Hi,

there are three features in Gecode that can result in nondeterministic behaviour: parallel search, search strategies based on AFC, and nonmonotonic propagators (currently circuit and nvalues).  If you don't use these features, the search trees will be exactly the same between runs (even for randomised strategies, as long as you don't change the random seed).  

Cheers,
Guido

-- 
Guido Tack
http://www.csse.monash.edu/~guidot/



On 29/06/2012, at 8:10 PM, Max Ostrowski wrote:

> I have a problem with my software clingcon, that uses gecode.
> 
> This piece of software is an SMT solver, that uses gecode as a theory
> solver.
> But i can also use it as a solver for arithmetic, without any SAT component.
> 
> Now my question: Is the behavior of Gecode reproducible.
> Whenever i start my program with exactly the same parameters, i do get
> the same result (same gecode statistics).
> When i change a parameter (like not printing the solution) i do get a
> different result (in terms of fails, nodes, etc... ).
> 
> The parameter i change should not affect Gecode at all (everything
> related to gecode is done with exactly the same input and in the same
> order).
> So do you use some memory position for hashing or some random generator
> initialized according to some position in memory or something else that
> explains this behavior.
> 
> Currently i get between 3 and 8615650 fails for a simple LatinSquare
> program, just because i change output formatting.
> 
> 
> PS:
> I tried this with gecode 3.5, 3.7 and trunk.
> I also tested the whole program with "valgrind --leak-check=full" and
> nothing uninitialized was used or lost.
> 
> 
> Any ideas?
> 
> Best,
> Max
> 
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