when do orthogonal projection $\ P_UP_V = P_VP_U$
10715
Orthogonal projection and two subspaces
29230
Orthogonality of Hermite functions
132595
$\sup_{0 \leq M \leq I_{\mathcal{H}_1}} \frac{\operatorname{Tr}[\rho M]}{\operatorname{Tr}[\sigma M]}$ satisfies Data Processing Inequality
59477
Density of orthogonal matrices with rational coefficients
138959
On the equality case of the Hölder and Minkowski inequalities
20844
Relations between p norms
129549
Showing that the orthogonal projection in a Hilbert space is compact iff the subspace is finite dimensional
71350
Let $H$ be a Hilbert space with projections $P,Q$, then $\lim_{n\to\infty}(PQ)^nx= Rx$ for all $x\in H$, where $R$ is the projection to $PH\cap QH$
15197
Relation between trace and rank for projection matrices
70657
aproximation in Sobolev Spaces
30017
Orthogonality and linear independence
84522
A better proof for $\det(P) = \pm1$ if $P$ is an orthogonal matrix
154628
What should we understand from the definition of orthogonality in inner product spaces other than $\mathbb R^n$?
89555
Inequality for the p norm of a convolution
60069
Orthogonal parametrization
92291
$U_1, U_2, ..., U_k$ subspaces of linear space $X$ with same dimensions, prove $X=U_1\oplus V=U_2\oplus V=...=U_k\oplus V$
146812
Explicit construction for unitary extensions of completely positive and trace preserving (CPTP) maps?