  We propose a generalized discrimination scheme for mixed quantum states. In
the present scenario we allow for certain fixed fraction of inconclusive
results and we maximize the success rate of the quantum-state discrimination.
This protocol interpolates between the Ivanovic-Dieks-Peres scheme and the
Helstrom one. We formulate the extremal equations for the optimal positive
operator valued measure describing the discrimination device and establish a
criterion for its optimality. We also devise a numerical method for efficient
solving of these extremal equations.
