Optimal Planning with Expressive Action Languages as Constraint Optimization

We consider the problem of optimal planning in deterministic domains specified with expressive action languages. We show how it is possible to reduce such problem to finding an optimal solution of a constraint optimization problem incorporating a bound n on the maximum length of the plan. By solving the latter, we can conclude whether (i) the plan found is optimal even for bounds greater than n; or (ii) we need to increase n; or (iii) it is useless to increase n since the planning problem has no solution.