Boundaries and polyhedral Banach spaces

Abstract: We show that if $X$ and $Y$ are Banach spaces, where $Y$ is separable and polyhedral, and if $T:X \to Y$ is a bounded linear operator such that $T^(Y^)$ contains a boundary $B$ of $X$, then $X$ is separable and isomorphic to a polyhedral space. Some corollaries of this result are presented.