Proving subspace of Banach space is finite dimensional
33642
Finite dimensional subspace of $C([0,1])$
109632
Show reflexive normed vector space is a Banach space
15560
Prove that the union of three subspaces of $V$ is a subspace iff one of the subspaces contains the other two.
155621
Finiteness of the dimension of a normed space and compactness
125623
Subspaces of separable normed spaces
4319
Vector space can be written as direct sum of subspaces
129549
Showing that the orthogonal projection in a Hilbert space is compact iff the subspace is finite dimensional
95513
Proving $W$ is a subspace of $P_{2}$
139367
Hahn Banach Theorem: Transfinite Induction
145952
Example of a closed subspace of a Banach space which is not complemented?
100161
Is it true that $\dim(X) \leq \dim(X^{\ast})$ for every infinite dimentional Banach space $X$?
150720
Given that $W$ is a subspace of $V$, prove: $\dim W=\dim V \implies W=V$
139272
On the norm of a quotient of a Banach space.
131993
Prove that vector space and dual space have same dimension
1799
How many k-dimensional subspaces there are in n-dimensional vector space over $\mathbb F_p$?
121047
Proof: Sum of dimension of orthogonal complement and vector subspace
97158
Prove that the operator norm is a norm