Measure, Integration & Real Analysis · Problem 10A.13
Linear Maps on Hilbert Spaces — Sheldon Axler
Mathematics — Measure Theory · left-right-invertible-open-sets
Problem
Suppose V is a Hilbert space.
(a) Show that {T∈B(V):T is left invertible} is an open subset of B(V).
(b) Show that {T∈B(V):T is right invertible} is an open subset of B(V).