Measure, Integration & Real Analysis · Problem 10B.16
Linear Maps on Hilbert Spaces — Sheldon Axler
Mathematics — Measure Theory · normal-operators-eigenvectors
Problem
Suppose {ek}k∈Z+ is an orthonormal basis of a Hilbert space V. Suppose also that T is a normal operator on V and ek is an eigenvector of T for every k≥2. Prove that e1 is an eigenvector of T.