We consider the classical Markowitz portfolio optimization problem with additional constraints representing so-called short sales.  The two objectives of this multiobjective problem are the expected return and the variance of a portfolio combined by a number of risky securities. A...

We consider the classical Markowitz portfolio optimization problem with additional constraints representing so-called short sales.  The two objectives of this multiobjective problem are the expected return and the variance of a portfolio combined by a number of risky securities. A...

In this paper, we deal with the construction of gap functions for variational inequalities by using an approach which bases on the conjugate duality. Under certain assumptions we also investigate a further class of gap functions for the variational inequality problem, the so-called dual gap...