assume that $a$, $b$ are banach algebras and that $m:atimes brightarrow b$, $m^prime:atimes arightarrow b$ are bounded bilinear mappings. we study the relationships between arens regularity of $m$, $m^prime$ and the banach algebras $a$, $b$. for a banach $a$-bimodule $b$, we show that $b$ factors with respect to $a$ if and only if $b^{**}$ is unital as an $a^{**}$-module. le...