Robust Performance and Structured Singular Quantifier Elimination

We consider the problem of computing the robust performance norm in %" or equivalently, the complex structured singular value. This problem is equivalent to tha.t of computing the %" norm of a function of several complex variables. We show how one can use Quantifier Elimination techniques to provide a test for whether the flm norm is less than one. These techniques can be viewed as a generalization of the use of Sturm's theorem to compute %" norms in the one variable case.