Strong Kharitonov theorems for low-order polynomials

The root clustering property of low-order interval polynomials is examined, and it is shown that the number of polynomials required to check root clustering within the left sector may be reduced if the order of the interval polynomial is low. Specifically, the reduction is possible if nφ<3π, where n is the order of the polynomial and φ is the damping angle that defines the left sector