Comments on 'a continuity proof of Rudin's theorem for polynomial and a generalization'

It is pointed out that main results, including the proof techniques of the recent publication by Curitn and Saba in 2000 and in 1996, are well known and have already appeared in the open literature in Basu and Fetteweis in 1987. The claimed simplification and novelty of proof techniques are not valid because the same method of using the continuity property that the zeros of polynomials have when viewed as functions of coefficients, with adequate refinements, had been used in Basu and Fetteweis in 1987, to arrive at the same set of results as discussed in Curitn and Saba in 2000, and in 1996. Index Terms--Multidimensional systems, recursive digital filters, stability, stable polynomials.