New posts in Operator Theory

Let $T(x_n)_{n \in \mathbb Z} = (x_{n+1})_{n \in \mathbb Z}$, proof that $\sigma(T) = S^1$.

a problem in functional analysis or operator theory

Is there an injective operator with a dense nonclosed one-codimensional range?

Prove that for the series $\sum_{n \in \mathbb{N}}|\zeta_n\mu_n|$ to be convergent for all $\zeta \in l^p \implies \mu \in l^q$

Definition of Essentially Self Adjoint Operators

Hilbert space adjoint vs Banach space adjoint?

Norm of the product of a self-adjoint operator and one of its spectral projections

Why does a unitary in the Calkin algebra always lift to an (co-)isometry?

Trace norm of a triangular matrix with only ones above the diagonal

$P+Q-PQ$ is a projection if and only if $PQ=QP$.