Orthogonal completion in nonhilbert spaces
65888
A counterexample to theorem about orthogonal projection
93165
A projection satisfying $\| Px \| \leq \|x\|$ for all $x$ is an orthogonal projection
92497
Isometric Embedding of a separable Banach Space into $\ell^{\infty}$
88153
Finding all inner products on $\mathbb{R}^2$ for which a given linear map is orthogonal
95759
Lower Semicontinuity Concepts
40820
Weak convergence in separable Hilbert spaces
97994
Orthogonality Relations Exercise, Brezis' Book Functional Analysis
57609
Hahn-Banach proof by extension of basis
78344
Nonconstant linear functional on a topological vector space is an open mapping
146812
Explicit construction for unitary extensions of completely positive and trace preserving (CPTP) maps?
125623
Subspaces of separable normed spaces
10715
Orthogonal projection and two subspaces
95928
Independence and orthogonality
108505
Matrix Concentration for Products- Orthogonality Property
156922
Proving convergence iff projection converges in product topology
98949
Subspaces and annihilators
95074
Separability of $l^{p}$ spaces