Abstract
In this paper, we obtain the solution to the discrete‐time, linear‐quadratic, finite‐horizon disturbance rejection problem, withhard boundson the disturbance and with a known or an unknown non‐zero initial state. It is shown that there exist two regions in the space of initial conditions: one where a pure‐strategy saddle point exists, and the other where no pure‐strategy saddle point exists. In the latter region, the structure of the minimax controller is fixed throughout, and a saddle point exists in the class of mixed policies. The paper also develops a general algorithm for the construction of such saddle points under different information structures, and illustrates this algorithm on a numerical example.