[gecode-users] Does Gecode compile to constraint-free code?

[Maik Riechert]

Hi all,

I'm quite new to the whole space of constraint programming and have 
recently made use of a finite domain constraint solving framework called 
monadiccp [1] for one of my current projects [2]. I measured the 
performance and saw that it was ~800x slower than my direct 
constraint-free implementation.

The framework also supports Gecode (apart from a pure Haskell 
implementation) but after seeing this slowdown I haven't tested it yet 
as the C-to-Haskell interfacing probabably also produces some overhead 
and I doubt it can get really fast.

I came across the paper "Compiling Constraint Solving using Projection" 
from Harvey et al [3] which I find quite promising. In my particular 
case I have very few (at the moment two) constraint systems which need 
to be solved thousands of times. They have 10-20 constraints and vary 
only in their input arguments, i.e. the constraints itself stay the same.

As the solver I use is a runtime solver which reads/simplifies/solves 
the whole system over and over, it is slow. The question is: Could the 
approach of the paper be used to derive constraint-free equations *once* 
and then use those in the actual algorithm? And does Gecode maybe 
support that already?

Cheers
Maik

[1] http://hackage.haskell.org/package/monadiccp/
[2] 
https://github.com/neothemachine/adp-multi/blob/master/src/ADP/Multi/Rewriting/ConstraintSolver.hs#L213
[3] 
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.17.3194&rep=rep1&type=pdf