A note on the new 1-D and 2-D stability theorems for discrete systems

An interesting theorem on the stability of 1-D discrete systems has been presented in [1] and it has been extended to the 2-D case in [2]. In this correspondence, after showing that the conditions stated by the theorems of [1] and [2] are only necessary, we introduce another condition, inclusion of which makes the above stability theorems necessary and sufficient.