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In this work, standard methods of the mixed thin-shell foramlism are refined using the framework of Colombeau's theory of generalized functions. To this end, systematic use is made of smooth generalized functions, in particular…

General Relativity and Quantum Cosmology · Physics 2025-05-07 Albert Huber

We define a general notion of set of indices which, using concepts from pre-ordered sets theory, permits to unify the presentation of several Colombeau-type algebras of nonlinear generalized functions. In every set of indices it is possible…

Functional Analysis · Mathematics 2014-08-07 Paolo Giordano , Eduard Nigsch

An explicit counterexample shows that contrary to the situation in the special Colombeau algebra, positivity and invertibility cannot be characterized pointwise in algebras of tempered generalized functions. Further a point value…

Functional Analysis · Mathematics 2008-08-07 Eberhard Mayerhofer

Using the existence of infinite numbers $k$ in the non-Archimedean ring of Robinson-Colombeau, we define the hyperfinite Fourier transform (HFT) by considering integration extended to $[-k,k]^{n}$ instead of $(-\infty,\infty)^{n}$. In order…

Functional Analysis · Mathematics 2022-10-03 Akbarali Mukhammadiev , Diksha Tiwari , Paolo Giordano

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

Modelling of singularities given by discontinuous functions or distributions by means of generalized functions has proved useful in many problems posed by physical phenomena. We introduce in a systematic way generalized functions of…

Functional Analysis · Mathematics 2010-07-12 Blagovest Damyanov

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

Generalized tensor analysis in the sense of Colombeau's construction is employed to introduce a nonlinear distributional pseudo-Riemannian geometry. In particular, after deriving several characterizations of invertibility in the algebra of…

Functional Analysis · Mathematics 2007-05-23 Michael Kunzinger , Roland Steinbauer

In a recent paper, we gave a topological description of Colombeau type algebras introducing algebras of sequences with exponential weights. Embeddings of Schwartz' spaces into the Colombeau algebra G are well known, but for…

Functional Analysis · Mathematics 2007-05-23 Antoine Delcroix , Maximilian F. Hasler , Stevan Pilipović , Vincent Valmorin

We present a construction of algebras of generalized functions of Colombeau-type which, instead of asymptotic estimates with respect to a regularization parameter, employs only topological estimates on certain spaces of kernels for its…

Functional Analysis · Mathematics 2017-04-27 Eduard A. Nigsch

We develop a refined theory of microlocal analysis in the algebra ${\mathcal G}(\Omega)$ of Colombeau generalized functions. In our approach, the wave front is a set of generalized points in the cotangent bundle of $\Omega$, whereas in the…

Functional Analysis · Mathematics 2017-05-24 Hans Vernaeve

Colombeau algebras constitute a convenient framework for performing nonlinear operations like multiplication on Schwartz distributions. Many variants and modifications of these algebras exist for various applications. We present a…

Functional Analysis · Mathematics 2013-07-02 E. A. Nigsch

This paper gives a comprehensive analysis of algebras of Colombeau-type generalized functions in the range between the diffeomorphism-invariant quotient algebra $\mathcal{G}^d = \mathcal{E}_M/\mathcal{N}$ introduced in part I and…

Functional Analysis · Mathematics 2007-05-23 Michael Grosser

Generalized Fourier integral operators (FIOs) acting on Colombeau algebras are defined. This is based on a theory of generalized oscillatory integrals (OIs) whose phase functions as well as amplitudes may be generalized functions of…

Analysis of PDEs · Mathematics 2008-03-04 Claudia Garetto

A simple pedagogical introduction to the Colombeau algebra of generalised functions is presented, leading the standard definition.

Functional Analysis · Mathematics 2013-08-02 Jonathan Gratus

Co lombeau's construction of generalized functions (in its special variant) is extended to a theory of generalized sections of vector bundles. As particular cases, generalized tensor analysis and exterior algebra are studied. A point value…

Functional Analysis · Mathematics 2007-05-23 Michael Kunzinger , Roland Steinbauer

We investigate homogeneity in the special Colombeau algebra. It is shown that strongly scaling invariant functions on the d-dimensional space are simply the constants. On the pierced space, strongly homogeneous functions admit tempered…

General Mathematics · Mathematics 2008-02-13 Clemens Hanel , Eberhard Mayerhofer , Stevan Pilipovic , Hans Vernaeve

We first propose a generalization of the notion of Mathieu subspaces of associative algebras $\mathcal A$, which was introduced recently in [Z4] and [Z6], to $\mathcal A$-modules $\mathcal M$. The newly introduced notion in a certain sense…

Representation Theory · Mathematics 2010-12-10 Wenhua Zhao

Normalizing Flows (NF) are powerful likelihood-based generative models that are able to trade off between expressivity and tractability to model complex densities. A now well established research avenue leverages optimal transport (OT) and…

Machine Learning · Computer Science 2023-04-17 Guillaume Morel , Lucas Drumetz , Simon Benaïchouche , Nicolas Courty , François Rousseau

The axiomatic formulation of quantum field theory (QFT) of the 1950's in terms of fields defined as operator valued Schwartz distributions is re-examined in the light of subsequent developments. These include, on the physical side, the…

Mathematical Physics · Physics 2007-05-23 H. Grosse , M. Oberguggenberger , I. T. Todorov