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Abstract
Everywhere in the text of the current paper, all our rings R are assumed to be associative, containing the identity element 1, which in general differs from the zero element 0. Our standard terminology and notations are mainly in agreement with [11]. For instance, for such a ring R, the letter J(R) stands for the Jacobson radical of R, Nil(R) for the set of nilpotents in R, and Id(R) for the set of idempotents in R. For some arbitrary but a fixed e Id(R), the subrings eRe and (1 - e)R(1 - e) of R are named corner subrings of R. As usual, Mn(R) will denote the full n n matrix ring, where n N.