How to find a linear injection $X\rightarrow X^\ast$ for general normed spaces?
115999
Is there always an injective map from a space in its dual space?
80618
Surjective bounded operator in Banach spaces without bounded right-inverse
22297
Normal operator $\Rightarrow$ S invariant implies $S^\perp$ invariant
17336
Least norm in convex set in Banach space
127488
If $L:\mathbb{R}^n \rightarrow \mathbb{R}^m$ and $m<n$ linear trans. What does this tell about injectivity and surjectivity?
78344
Nonconstant linear functional on a topological vector space is an open mapping
105852
How to verify whether or not there exists a vector $x$ such that $Ax > 0$?
148804
Norm-Euclidean rings?
98759
Proof of "Dual normed vector space is complete"
7345
Is $C[0,1]$ a Banach space for the $L^1$ norm?
51177
When are two norms equivalent on a Banach space?
151752
Example of a linear operator on some vector space with more than one right inverse.
145535
Product norm on infinite product space
69766
Is every normed vector space, an inner product space
57619
Norms Induced by Inner Products and the Parallelogram Law
143869
Showing that the norm of the canonical projection $X\to X/M$ is $1$
55067
Norm of self-adjoint operator