Observables and Derivables. Part I: Special Types

摘要

This paper is concerned with special types of observables and derivables and the relationships between them. In particular, we consider special types of derivables classified according to their spectra and then characterize these derivables in ways which are independent of this spectra. Derivables with countable spectra are considered; compact derivables are treated; bounded derivables are considered; and derivables with positive spectra and spectra with unit modulus are discussed. Uniqueness and existence properties of bounded observables are discussed. (Author)