2 problems

Let $\mathcal{L}$ be a rank-one perturbation of a compact normal operator. An invariant subspace with a common spectral part is an invariant subspace $\mathcal{M}$ satisfying … for…

Let $T$ be a self-adjoint operator and let $D(\lambda)$ denote the difference of the spectral projections associated with $T$ and a rank-one perturbation, as in Proposition 3. The…