an equivalent condition for a projection on a Hilbert space
119684
Is a contraction idempotent operator self-adjoint?
133609
orthonormal system in a Hilbert space
93165
A projection satisfying $\| Px \| \leq \|x\|$ for all $x$ is an orthogonal projection
38019
Projection is an open map
17159
Proof of Closest Point Theorem in Hilbert Space
121106
Parallelogram law valid in banach spaces?
118996
Prove that $T$ is an orthogonal projection
55533
Tensor Product: Hilbert Spaces
144019
A strictly positive operator is invertible
31302
Hilbert Schmidt Norm-Rank-inequality
153634
A statment about the equivalence between the Axiom of Choice and the surjectivity of the projections.
95901
Inequality similar to the Schwarz-Pick theorem
51302
Show that the operator norm is submultiplicative
87897
Bounded operators on separable Hilbert spaces
155317
Norm of adjoint operator in Hilbert space
126133
Conditional convergence, Mertens theorem
154913
Are all the norms of $L^p$ space equivalent?