Oblique projections on metric spaces

Matteo Polettini

It is known that complementary oblique projections ${\hat{P}}_0+{\hat{P}}_1=I$ on a Hilbert space $\mathcal{H}$ have the same standard operator norm $\Vert {\hat{P}}_0\Vert =\Vert {\hat{P}}_1\Vert$…