The Kaplansky condition and rings of almost stable range 1 (1107.3000v1)

Abstract: We present some variants of the Kaplansky condition for a K-Hermite ring $R$ to be an elementary divisor ring; for example, a commutative K-Hermite ring $R$ is an EDR iff for any elements $x,y,z\in R$ such that $(x,y)=(1)$, there exists an element $\lambda\in R$ such that $x+\lambda y=uv$, where $(u,z)=(v,1-z)=(1)$. We present an example of a a B\'ezout domain that is an elementary divisor ring, but it does not have almost stable range 1, thus answering a question of Warren Wm. McGovern.