Maher P.J. Operator Approximant Problems Arising from Quantum Theory

Springer International Publishing AG, 2017. — 110 p. — ISBN: 3319611690.This book offers an account of a number of aspects of operator theory, mainly developed since the 1980s, whose problems have their roots in quantum theory. The research presented is in non-commutative operator approximation theory or, to use Halmos' terminology, in operator approximants. Focusing on the concept of approximants, this self-contained book is suitable for graduate courses.What This Book Is About: Approximants
Preliminaries
Self-Adjoint and Positive Approximants
Commutator Approximants
Spectral, and Numerical Range, Approximants
Unitary, Isometric and Partially Isometric Approximation of Positive Operators