Measure, Integration & Real Analysis · Problem 6C.6
Banach Spaces — Sheldon Axler
Mathematics — Measure Theory · bounded-functions-banach-space
Problem
Suppose X is a nonempty set and b(X) is the vector space of bounded functions from X to F. Prove that if ∥⋅∥ is defined on b(X) by ∥f∥=supX∣f∣, then b(X) is a Banach space.