From division to extension

Abstract

We present a short proof of a version of the Ohsawa-Takegoshi-Manivel $L^2$ extension theorem as a corollary of a Skoda-type $L^2$ division theorem with bounded generators. The new division theorem is of independent interest: the boundedness of generators allows to send the parameter $\alpha>1$ of the usual $L^2$ division theorems to 1 in the norm of the datum of the division. As an aside, we also use the new division theorem to prove a Brian\c{c}on-Skoda-type result.