Hi all,
I am working on an optimization problem defined using constraints,
to compute the lowest energy model of a protein lattice. My variables are
implemented as integer variables that refer to a pool of protein fragments,
and I wish to implement an optimization function that - given an assignment
of all variables - returns an energy value (double) that should be minimized.
So far, I've implemented the optimization as follows:
- in the model constructor, I use synchronized execution to call a function
c when all variables become assigned (using wait(Space&, IntVarArray&, c&)
- a static variable that holds the best energy so far
static BEST_ENERGY = 10000;
- the continuation function c looks something like
static void c(Space& _home) {
// compute energy using assigned variables
double energy = ...;
if(energy > BEST_ENERGY) {
// fail if energy is worse
home.fail();
} else {
BEST_ENERGY = energy;
}
}
This works fine, and I can use different search algorithms to traverse the tree
and move into the direction of lowest energy. However, I am not sure if this is
the
correct way. Initially, I thought about implementing the cost() function but
quickly
discarded it because it only seems to work with integer variables. Also using
the
constrain function I need to use a static variable as well, and I don't know
what
kind of constrained I should post there (the energy function can not prune
domains,
it can either accept it as better or fail the space..)
Thanks for the clarification!
Peter
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