On BIBO- stability and nonessential singularities of the second kind

The open problem of the BIBO-stability of 2-D digital filters in the presence of nonessential singularities of the second kind on the distinguished boundary of the unit bidisk has attracted a lot of interest in the recent past [1]-[5]. One of the reasons for its importance is the practical need for the generation of BIBO-stable digital filters at the design stage.