Search results for "Opera"

The Dynamical Problem for a Non Self-adjoint Hamiltonian

2012

After a compact overview of the standard mathematical presentations of the formalism of quantum mechanics using the language of C*- algebras and/or the language of Hilbert spaces we turn attention to the possible use of the language of Krein spaces.I n the context of the so-called three-Hilbert-space scenario involving the so-called PT-symmetric or quasi- Hermitian quantum models a few recent results are reviewed from this point of view, with particular focus on the quantum dynamics in the Schrodinger and Heisenberg representations.

Elliptic convolution operators on non-quasianalytic classes

2001

For those nonquasianalytic classes in which an extension of the classical Borel's theorem holds we show that every elliptic convolution operator is the composition of a translation and an invertible ultradifferential operator. This answers a question asked by Chou in: La transformation de Fourier complexe et l'equation de convolution, LNM 325, Berlin-Heidelberg-New York (1973).

Fibred Categories and the Six Functors Formalism

2019

In Section 1, we introduce the basic language used in this book, the so-called premotivic categories and their functoriality. This is an extension of the classical notion of fibered categories. They appear with different categorical structures. In Section2, the language of premotivic categories is specialized to that of triangulated categories and to algebraic geometry. We introduce several axioms of such categories which ultimately will lead to the full six functors formalism. An emphasis is given on the study of the main axioms, with a special care about the so-called localization axiom. Then in Section 3, the general theory of descent is formulated in the language of premotivic model cat…

Equivalences involving (p,q)-multi-norms

2014

O* - Dynamical Systems and * - Derivations of Unbounded Operator Algebras

1999

A spatial theory is developed for * - derivations of an algebra of unbounded operators, in terms of the concept of O*-dynamical systems. Three notions of spatiality emerge, depending on the nature of the corresponding generator. Special emphasis is put on O*-dynamical systems generated by one-parameter groups of *-automorphisms and their *-derivations.

Symmetries in Spaces, Symmetries in Listening

2018

Based on the importance of the concept of symmetry in French sociological aesthetics circa 1900, this chapter analyzes the convergence of theaters, musical form, and musical understanding. The analysis focuses on architectural shape, audience response, and the musical repertoire in the new theaters built in Barcelona (1847), Paris (1862), and Rome (1880). While these theaters were fashioned after the baroque form of the “teatro all’italiana” that prevailed in Italy, France, and Spain during the late nineteenth century, they provided huge spaces accommodating a socially mixed audience within an architecturally symmetrical form. Music critics often aligned acoustic sound waves with actual vis…

On Conditioning Operators

1999

The construction of conditional events (so-called measure-free conditioning) has a long history and is one of the fundamental problems in non-deterministic system theory (cf. [6]). In particular, the iteration of measure-free conditioning is still an open problem. The present paper tries to make a contribution to this question. In particular, we give an axiomatic introduction of conditioning operators which act as binary operations on the universe of events. The corresponding axiom system of this type of operators focus special attention on the intuitive understanding that the event ‘α given β’ is somewhere in “between” ‘α and β’ and ‘β implies α’. A detailed motivation of these axioms can …

Spectrum and Pseudo-Spectrum

2019

In this book all Hilbert spaces will be assumed to separable for simplicity. In this section we review some basic definitions and properties; we refer to Kato (Perturbation theory for linear operators, Die Grundlehren der mathematischen Wissenschaften, Band 132. Springer, New York, 1966), Reed and Simon (Methods of modern mathematical physics. I. Functional analysis, 2nd edn. Academic, New York, 1980; Methods of modern mathematical physics. II. Fourier analysis, self adjointness. Academic, New York, 1975; Methods of modern mathematical physics. IV. Analysis of operators. Academic, New York, 1978), Riesz and Sz.-Nagy (Lecons d’analyse fonctionnelle, Quatrieme edition. Academie des Sciences d…

Current Algebras as Hilbert Space Operator Cocycles

1994

Aspects of a generalized representation theory of current algebras in 3 + 1 dimensions axe discussed. Rules for a systematic computation of vacuum expectation values of products of currents are described. Their relation to gauge group actions in bundles of fermionic Fock spaces and to the sesquilinear form approach of Langmann and Ruijsenaars is explained. The regularization for a construction of an operator cocycle representation of the current algebra is explained. An alternative formula for the Schwinger terms defining gauge group extensions is written in terms of Wodzicki residue and Dixmier trace.

On many-sorted algebraic closure operators

2004

A theorem of Birkhoff-Frink asserts that every algebraic closure operator on an ordinary set arises, from some algebraic structure on the set, as the corresponding generated subalgebra operator. However, for many-sorted sets, i.e., indexed families of sets, such a theorem is not longer true without qualification. We characterize the corresponding many-sorted closure operators as precisely the uniform algebraic operators. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)