An extreme point result for robust stability of discrete-time interval polynomials

For the case of discrete-time interval polynomials, the attainment of Kharitonov-like extreme point results has been a focal point of recent research. To date, the strongest available result is applicable subject to the restriction that the coefficients of z^k are fixed for k> the greatest integer less than or equal to n/2, where n is the degree of the interval polynomial. Conditions are given under which perturbations can be tolerated in the higher order coefficients while preserving the property that stability of the extreme polynomials implies stability of the entire family