A simple proof of Rudin's multivariable stability theorem
P. Delsarte, Yves V. Genin, Yves Kamp · IEEE Transactions on Acoustics Speech and Signal Processing · 1980
It is shown how Rudin's multivariable stability theorem can be proved by using simple one-variable arguments, exclusively. In particular, no use is made of multivariable homotopy, in contrast with the original proof. The efficacy of the approach presented here is further illustrated by deriving a new stability test as well as elementary and independent proofs for the classical criteria.