Proving that the spectral norm of a matrix is orthogonally invariant
117175
Proof that the 2-norm of orthogonal transformation of a matrix is invariant
143869
Showing that the norm of the canonical projection $X\to X/M$ is $1$
11911
How to prove the positive definite property of the semidefinite matrix with regularization?
65888
A counterexample to theorem about orthogonal projection
62590
Show norm preserving property and determine Eigenvalues
109471
The eigenvectors of the transpose operator
46435
2-norm of the orthogonal projection
35625
Direct sum of orthogonal subspaces
54668
Proof for the completeness of eigenfunctions of a self-adjoint operator
51302
Show that the operator norm is submultiplicative
106288
Prove that the eigenvalues of a block matrix are the combined eigenvalues of its blocks
48111
Invariant Subspace of Two Linear Involutions
4509
Proof that an involutory matrix has eigenvalues 1,-1
113779
If $P$ is an orthogonal matrix its columns form an orthonormal set.
124095
$A$ is a real orthogonal matrix, prove that $ (I+A)^{-1}(I-A)$ is skew-symmetric
59409
Show Laplace operator is rotationally invariant
146405
Norm with symmetric positive definite matrix