On the inset of a convergence domain

Abstract:

Let A be a conservative matrix. The main purpose of this article is to give a negative answer to the open question E raised by Macphail and Wilansky [1], namely, “If $\Lambda _A^ \bot = {I_A}$, must $\Lambda _D^ \bot = {I_D}$ for every matrix D with ${c_D} = {c_A}$?".