On comparison between Apostolatos–Kulisch and Mayer–Warnke theorems in interval analysis

This paper deals with comparing Apostolatos–Kulisch theorem and Mayer–Warnke theorem that form a basis of the so-called formal (aka algebraic) approach to the outer interval estimation of the solution sets for interval linear systems of equations. We show that despite a greater generality of Mayer–Warnke theorem, it extends the applicability scope of the formal approach to a very small extent, and a practical significance of such an extension is inessential.