Penalty method for cardinality constrained optimization problems with an application in portfolio theory
摘要
In this paper, we focus on nonlinear programming problems with cardinality constraints that restrict the number of nonzero components of the decision vector. We start with a straightforward mixed-integer programming reformulation. Inspired by previous papers, the binary restrictions on variables are then relaxed, leading to a large number of stationary points based on the Karush-Kuhn-Tucker optimality conditions. Therefore, we employ so-called binary penalties that penalize the non-binary values in the decision vector. This leads to a desirable reduction in the number of stationary points. In the numerical part, we compare the solution approaches on test instances of a portfolio selection problem.