Which multiplication operators are surjective isometries?

Eugene Bilokopytov

Published 2019-01-02Version 1

Let $\mathbf{F}$ be a Banach space of continuous functions over a connected locally compact space $X$. We present several sufficient conditions on $\mathbf{F}$ guaranteeing that the only multiplication operators on $\mathbf{F}$ that are surjective isometries are scalar multiples of the identity. The conditions are given via the properties of the inclusion operator from $\mathbf{F}$ into $\mathcal{C}\left(X\right)$, as well as in terms of geometry on $\mathbf{F}$. An important tool in our investigation is the notion of Birkhoff Orthogonality.