Set-functions and factorization

Abstract

If $\varphi$ is a submeasure satisfying an appropriate lower estimate we give a quantitative result on the total mass of a measure $\mu$ satisfying $0\le \mu \le \varphi .$ We give a dual result for supermeasures and then use these results to investigate convexity on non-locally convex quasi-Banach lattices. We then show how to use these results to extend some factorization theorems due to Pisier to the setting of quasi-Banach spaces. We conclude by showing that if $X$ is a quasi-Banach space of cotype two then any operator $T:C(\Omega )\to X$ is 2-absolutely summing and factors through a Hilbert space and discussing general factorization theorems for cotype two spaces.