The CS decomposition and conditional negative correlation inequalities for determinantal processes

For a conditional process of the form $(\phi \vert A_{i} \not\subset \phi)$ where $\phi$ is a determinantal process we obtain a new negative correlation inequalities. Our approach relies upon the underlying geometric structure of the elementary discrete determinantal processes by using the canonical representation of a pair of subspaces in terms of principal vectors and angles, as well as the classical CS decomposition.