Introduction to Hilbert Space and the Theory of Spectral Multiplicity

New York: Chelsea Publishing, 1957 8vo (23.5 cm), 114, [12] pp. Publisher's cloth, gilt-lettered spines (bindings slightly rubbed, endpapers toned, ownership entry on the front free endpaper). "My main reason for writing this book was to make available to English-speaking students the result of Chapter III, the so-called multiplicity theory. The theory as I present it deals with arbitrary spectral measures and includes, consequently, the multiplicity theory of (bounded and unbounded) normal operators on a not necessarily separable Hilbert space, and includes, as another useful special case, the multiplicity theory of unitary representations of locally compact abelian groups." (from the Preface) Paul Richard Halmos (1916-2006) was a Hungarian-born American mathematician who made fundamental advances in the areas of mathematical logic, probability theory, statistics, operator theory, ergodic theory, and functional analysis.