Self-adjoint compact operator on a Hilbert space cannot be surjective
44738
Compact operators on an infinite dimensional Banach space cannot be surjective
11109
The ideal generated by a non-compact operator
39842
Limit point Compactness does not imply compactness counter-example
136909
Functional Analysis: The rank of an operator detemines if it's a compact operator.
35982
A function and its Fourier transform cannot both be compactly supported
50946
Separable Hilbert space have a countable orthonormal basis
149997
Convolution operator has norm 1 with respect to $L^2$ norm
151046
Closure of the invertible operators on a Banach space
45249
Pseudocompactness does not imply compactness
55067
Norm of self-adjoint operator
80735
Show that $C_0([a, b], \mathbb{R})$ is not $\sigma$-compact
151347
Why do operators belonging to different Hilbert spaces commute?
11159
Problem about a compact operator $T:l^p\rightarrow l^p$
52198
Why is every selfadjoint operator closed?
8698
Show the Volterra Operator is compact using only the definition of compact
154226
Upper bound for norm of Hilbert space operator
128361
The kernel and range of the powers of a self-adjoint operator