Subset of separable Hilbert space
125623
Subspaces of separable normed spaces
108807
Subset of a cartesian product
146455
Compactness of the set of all unitary matrices in $M_2(\mathbb{C})$
6793
A linearly independent set about approximate units
115954
how to find maximal linearly independent subsets
66299
Operator whose spectrum is given compact set
49438
Prove that $X^\ast$ separable implies $X$ separable
32420
A complete orthonormal system contained in a dense sub-space.
123061
$X$ metric separable then $C(X)$ separable
90826
Constructing a subset not in $\mathcal{B}(\mathbb{R})$ explicitly
94844
Unitary map between sets of vectors
86481
Let $H$ be an infinite-dimensional separable Hilbert space, show that a Hilbert-Schmidt operator is compact
16692
a representation condition of Hilbert space
130045
Show that $l^2$ is a Hilbert space
136108
Arbitrary intersection of closed, connected subsets of a compact space connected?
140711
Linear independence of images by $A$ of vectors whose span trivially intersects $\ker(A)$
95481
The set of self-adjoint operators over a Hilbert space doesn't form a lattice