Developing Efficient Cooperative Solvers for Constrained Optimization

Yi Shang, Markus P.J. Fromherz, and Ying Zhang

Abstract

When it is impossible to find an optimal solution of a nonlinear constrained optimization problems within a limited amount of time, the goal usually becomes finding a sub-optimal solution as good as possible. In this paper, we study time and quality trade-offs on continuous constrained optimization problem. We focus on cooperative solvers that consist of two optimization methods, sequential quadratic programming (SQP) and quasi-Newton method, and experiment with a sequential form of composition: quasi-Newton followed by SQP. In the experiments, we analyze the performance of the cooperative solvers on a series of problems with increasing constraint-to-variable ratios, and compare that with SQP in terms of number of function evaluation and solution quality. The cooperative solvers generally get much better solutions than SQP, while spending comparable amount of time. They are flexible and could achieve good results on time-bounded applications by setting parameters according to the time limits.

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