Order continuous extensions of positive compact operators on Banach lattices

Abstract

Let $E$ and $F$ be Banach lattices. Let $G$ be a vector sublattice of $E$ and $T:G\to F$ be an order continuous positive compact (resp. weakly compact) operators. We show that if $G$ is an ideal or an order dense sublattice of $E$, then $T$ has a norm preserving compact (resp. weakly compact) positive extension to $E$ which is likewise order continuous on $E$. In particular, we prove that every compact positive orthomorphism on an order dense sublattice of $E$ extends uniquely to a compact positive orthomorphism on $E$.

7 pages