Robust stability of delay difference systems under fractional perturbations in infinite-dimensional spaces

In this article we study the robust stability of difference systems with delays under fractional perturbations in infinite-dimensional spaces. First, the estimates of the complex stability radius are addressed. Second, it is shown that for positive linear systems, the complex, real and positive stability radii coincide and can be computed by a simple formula. Finally, a simple example is given to illustrate the obtained results.