“…The input-output methods or the so-called "theorems of Perron type" have proved to be important tools in the study of the asymptotic behavior of difference equations like stability see 27,29,30 , expansiveness see 6 , dichotomy see 1,5,8,15,17,19,20,32 , and trichotomy as well see 7, 18, 20 . A distinct method for the study of exponential stability relies on the convergence of some associated series and this was used in 28 for difference equations and in 4 for variational difference equations. The exponential stability of difference equations with several variable delays and variable coefficients was studied in 16 , where the authors obtained interesting conditions for global exponential stability using new computational formulas with respect to the coefficients.…”