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A new method is presented for assigning distributional curvature, in an invariant manner, to a space-time of low differentiability, using the techniques of Colombeau's `new generalised functions'. The method is applied to show that…

General Relativity and Quantum Cosmology · Physics 2009-10-28 C J S Clarke , J A Vickers , J P Wilson

In these lecture notes we present an introduction to non-standard analysis especially written for the community of mathematicians, physicists and engineers who do research on J. F. Colombeau' theory of new generalized functions and its…

Functional Analysis · Mathematics 2010-10-19 Todor D. Todorov

This paper is a tutorial that demonstrates various methods from the Colombeau theory of generalized functions in the context of semilinear wave equations. The Colombeau generalized functions constitute differential algebras that contain the…

Analysis of PDEs · Mathematics 2007-05-23 Michael Oberguggenberger

This paper builds on the theory of generalised functions begun in [1]. The Colombeau theory of generalised scalar fields on manifolds is extended to a nonlinear theory of generalised tensor fields which is diffeomorphism invariant and has…

Functional Analysis · Mathematics 2021-03-17 Eduard A. Nigsch , James A. Vickers

We characterize microlocal regularity of Colombeau generalized functions by an appropriate extension of the classical notion of micro-ellipticity to pseudodifferential operators with slow scale generalized symbols. Thus we obtain an…

Analysis of PDEs · Mathematics 2007-05-23 Claudia Garetto , Guenther Hoermann

In this paper we review the extent to which one can use classical distribution theory in describing solutions of Einstein's equations. We show that there are a number of physically interesting cases which cannot be treated using…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Roland Steinbauer , James A. Vickers

Colombeau's generalized functions are used to adapt the distributional approach to singular hypersurfaces in general relativity with signature change. Equations governing the dynamics of singular hypersurface is obtained and it is shown…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Reza Mansouri , Kourosh Nozari

We present an extension of the methods of classical Lie group analysis of differential equations to equations involving generalized functions (in particular: distributions). A suitable framework for such a generalization is provided by…

Functional Analysis · Mathematics 2007-05-23 Michael Kunzinger , Michael Oberguggenberger

We construct an algebra of generalized functions endowed with a canonical embedding of the space of Schwartz distributions. We offer a solution to the problem of multiplication of Schwartz distributions similar to but different from…

Functional Analysis · Mathematics 2008-10-08 Todor D. Todorov , Hans Vernaeve

This paper is devoted to strictly hyperbolic systems and equations with non-smooth coefficients. Below a certain level of smoothness, distributional solutions may fail to exist. We construct generalised solutions in the Colombeau algebra of…

Analysis of PDEs · Mathematics 2011-08-12 Claudia Garetto , Michael Oberguggenberger

We present an extension of J. F. Colombeau's theory of nonlinear generalized functions to spaces of generalized sections of vector bundles. Our construction builds on classical functional analytic notions, which is the key to having a…

Functional Analysis · Mathematics 2016-02-19 Eduard A. Nigsch

We introduce the notion of functionally compact sets into the theory of nonlinear generalized functions in the sense of Colombeau. The motivation behind our construction is to transfer, as far as possible, properties enjoyed by standard…

Functional Analysis · Mathematics 2016-03-01 Paolo Giordano , Michael Kunzinger

A unified, fast, and effective approach is developed for numerical calculation of the well-known plasma dispersion function with extensions from Maxwellian distribution to almost arbitrary distribution functions, such as the $\delta$, flat…

Plasma Physics · Physics 2013-11-20 Hua-sheng Xie

We give an overview of the development of algebras of generalized functions in the sense of Colombeau and recent advances concerning diffeomorphism invariant global algebras of generalized functions and tensor fields. We furthermore provide…

Functional Analysis · Mathematics 2014-07-01 Eduard A. Nigsch , Clemens Sämann

Algebras of generalized functions offer possibilities beyond the purely distributional approach in modelling singular quantities in non-smooth differential geometry. This article presents an introductory survey of recent developments in…

Functional Analysis · Mathematics 2007-05-23 Michael Kunzinger

We present a differential algebra of generalized functions over a field of generalized scalars by means of several axioms in terms of general algebra and topology. Our differential algebra is of Colombeau type in the sense that it contains…

Functional Analysis · Mathematics 2014-05-29 Todor D. Todorov

This is a gentle introduction to Colombeau nonlinear generalized functions, a generalization of the concept of distributions such that distributions can freely be multiplied. It is intended to physicists and applied mathematicians who…

Mathematical Physics · Physics 2008-10-06 Andre Gsponer

Based on a refinement of the notion of internal sets in Colombeau's theory, so-called strongly internal sets, we introduce the space of generalized smooth functions, a maximal extension of Colombeau generalized functions. Generalized smooth…

Functional Analysis · Mathematics 2016-09-15 Paolo Giordano , Michael Kunzinger , Hans Vernaeve

Generalized smooth functions are a possible formalization of the original historical approach followed by Cauchy, Poisson, Kirchhoff, Helmholtz, Kelvin, Heaviside, and Dirac to deal with generalized functions. They are set-theoretical…

Functional Analysis · Mathematics 2016-06-14 Paolo Giordano , Michael Kunzinger

We develop the diffeomorphism invariant Colombeau-type algebra of nonlinear generalized functions in a modern and compact way. Using a unifying formalism for the local setting and on manifolds, the construction becomes simpler and more…

Functional Analysis · Mathematics 2013-03-14 Eduard Nigsch
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