Operator theory is a diverse area of mathematics which derives its motivation from several sources, including branches of physics and mechanics. This introduction to operator theory discusses the necessary background, as well as some more advanced topics. This new edition includes source notes, commentary on proofs, and problems of varying difficulty.
The structure theorems here are extremely elegant and the high-level organization of the results is quite good, but the proofs are a bit technical, and it could often be much easier to convey the underlying (simple) ideas than in a technical paragraph of explanation.