Search results for "Symbol"

Hartmanis-Stearns Conjecture on Real Time and Transcendence

2012

Hartmanis-Stearns conjecture asserts that any number whose decimal expansion can be computed by a multitape Turing machine is either rational or transcendental. After half a century of active research by computer scientists and mathematicians the problem is still open but much more interesting than in 1965.

CY-Operators and L-Functions

2019

This a write up of a talk given at the MATRIX conference at Creswick in 2017 (to be precise, on Friday, January 20, 2017). It reports on work in progress with P. Candelas and X. de la Ossa. The aim of that work is to determine, under certain conditions, the local Euler factors of the L-functions of the fibres of a family of varieties without recourse to the equations of the varieties in question, but solely from the associated Picard–Fuchs equation.

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 …

Gibbs measures in a markovian context and dimension

2001

LORENTZ SPACES OF VECTOR-VALUED MEASURES

2003

Noether’s Early Contributions to Modern Algebra

2020

As described in preceding chapters, Noether’s work on invariant theory broke new ground that led the Gottingen mathematicians, but first and foremost Hilbert, to invite her to habilitate there.

Multiplication of Distributions in One Dimension: Possible Approaches and Applications to δ-Function and Its Derivatives

1995

We introduce a new class of multiplications of distributions in one dimension merging two different regularizations of distributions. Some of the features of these multiplications are discussed in detail. We use our theory to study a number of examples, involving products between Dirac delta functions and its successive derivatives. © 1995 Academic Press. All rights reserved.

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…

Analytic vectors, anomalies and star representations

1989

It is hinted that anomalies are not really anomalous since (at least in characteristic examples) they can be related to a lack of common analytic vectors for the Hamiltonian and the observables. We reanalyze the notions of analytic vectors and of local representations of Lie algebras in this light, and show how the notion of preferred observables introduced in the deformation (star product) approach to quantization may help give an anomaly-free formulation to physical problems. Finally, some remarks are made concerning the applicability of these considerations to field theory, especially in two dimensions.

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.