Questo conciso trattamento introduttivo è composto da tre capitoli: The Geometry of Hilbert Space, The Algebra of Operators e The Analysis of Spectral Measures. Un background in teoria della misura è l'unico prerequisito. 'Un'esposizione sempre fresca, dimostrazioni sofisticate e una scelta di argomenti certamente attuale'. — Bulletin of the American Mathematical Society.
Hungarian-born Paul R. Halmos (1916–2006) is widely regarded as a top-notch expositor of mathematics. He taught at the University of Chicago and the University of Michigan as well as other universities and made significant contributions to several areas of mathematics, including mathematical logic, probability theory, ergodic theory, and functional analysis.