Measure, Integration & Real Analysis · Problem 6E.14
L^p Spaces — Sheldon Axler
Mathematics — Measure Theory · bounded-inverse-theorem-v-not-banach
Problem
Show that there exists a normed space V, a Banach space W, and a one-to-one bounded linear map T of V onto W such that T−1 is not a bounded linear map of W onto V.
[This exercise shows that the hypothesis in the Bounded Inverse Theorem (6.83) that V is a Banach space cannot be relaxed to the hypothesis that V is a normed vector space.]