  Numerical analysis has no satisfactory method for the more realistic
optimization models. However, with constraint programming one can compute a
cover for the solution set to arbitrarily close approximation. Because the use
of constraint propagation for composite arithmetic expressions is
computationally expensive, consistency is computed with interval arithmetic. In
this paper we present theorems that support, selective initialization, a simple
modification of constraint propagation that allows composite arithmetic
expressions to be handled efficiently.
