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We introduce abelian framed bicategories, which are particular framed bicategories that are locally abelian, and show that they are suitable for developing homology and cohomology theories for directed structures. This means in particular…

Category Theory · Mathematics 2026-02-05 Augustin Albert , Jérémy Dubut , Eric Goubault

Consider a positive Borel measure on a locally compact group. We define a notion of uniform density for such a measure, which is based on a group invariant introduced by Leptin in 1966. We then restrict to unimodular amenable groups and to…

Group Theory · Mathematics 2024-09-05 Felix Pogorzelski , Christoph Richard , Nicolae Strungaru

In this paper we study unimodular amenable groups. The first part is devoted to results on the existence of uniform families of epsilon-quasi tilings for these groups. In this context, constructions of Ornstein and Weiss are extended by…

Spectral Theory · Mathematics 2013-07-31 Felix Pogorzelski , Fabian Schwarzenberger

We present a general framework to represent discrete configuration systems using hypergraphs. This representation allows one to transfer combinatorial removal lemmas to their analogues for configuration systems. These removal lemmas claim…

Combinatorics · Mathematics 2015-05-12 Lluís Vena

In this paper we study injective modules over universal enveloping algebras of finite-dimensional Lie algebras over fields of arbitrary characteristic. Most of our results are dealing with fields of prime characteristic but we also…

Representation Theory · Mathematics 2007-05-23 Joerg Feldvoss

We introduce the notion of being cohomologically complete for objects of the derived category of sheaves of $Z[\hbar]$-modules on a topological space. Then we consider a $Z[\hbar]$-algebra satisfying some suitable conditions and prove…

Quantum Algebra · Mathematics 2010-03-22 Masaki Kashiwara , Pierre Schapira

Several authors have introduced various type of coherent-like rings and proved analogous results on these rings. It appears that all these relative coherent rings and all the used techniques can be unified. In [2], several coherent-like…

Commutative Algebra · Mathematics 2020-09-01 Mostafa Amini , Arij Benkhadra , Bennis , Mohammed Hajoui

We study conformally invariant boundary conditions that break part of the bulk symmetries. A general theory is developped for those boundary conditions for which the preserved subalgebra is the fixed algebra under an abelian orbifold group.…

High Energy Physics - Theory · Physics 2009-10-31 J. Fuchs , C. Schweigert

This paper provides new sufficient and necessary conditions for the frame property of generalized translation-invariant systems. The conditions are formulated in the Fourier domain and consists of estimates involving the upper and lower…

Functional Analysis · Mathematics 2022-01-20 Jakob Lemvig , Jordy Timo van Velthoven

We study certain moduli spaces of stable vector bundles of rank two on cubic and quartic threefolds. In many cases under consideration, it turns out that the moduli space is complete and irreducible and a general member has vanishing…

Algebraic Geometry · Mathematics 2008-04-21 Indranil Biswas , Jishnu Biswas , G. V. Ravindra

It is well known that for irreducible, square-integrable representations of a locally compact group, there exist so-called admissible vectors which allow the construction of generalized continuous wavelet transforms. In this paper we…

Functional Analysis · Mathematics 2016-09-07 Hartmut Fuehr

In this paper we present a unified proof of the fact that the category of modules over a ring and the category of near-vector spaces in the sense of J. Andr\'e, over an appropriate scalar system (a 'scalar group'), are both abelian…

Rings and Algebras · Mathematics 2025-01-29 Zurab Janelidze , Sophie Marques , Daniella Moore

Let $(C,\underline{w})$ be a polarized nodal reducible curve. In this paper we consider coherent systems of type $(r,d,k)$ on $C$ with $k < r$. We prove that the moduli spaces of $(\underline{w},\alpha)$-stable coherent systems stabilize…

Algebraic Geometry · Mathematics 2022-02-10 Sonia Brivio , Filippo F. Favale

We give a short geometric proof of a result of Soardi & Woess and Salvatori that a quasitransitive graph is amenable if and only if its automorphism group is amenable and unimodular. We also strengthen one direction of that result by…

Group Theory · Mathematics 2023-06-16 Romain Tessera , Matthew Tointon

Let p be an odd prime. We show that the classification of p-divisible groups by Breuil windows and the classification of finite flat group schemes of p-power order by Breuil modules hold over any complete regular local ring with perfect…

Number Theory · Mathematics 2009-09-01 Eike Lau

We show that the homogeneous approximation property and the comparison theorem hold for arbitrary coherent frames. This observation answers some questions about the density of frames that are not covered by the theory of Balan, Casazza,…

Functional Analysis · Mathematics 2010-12-21 Karlheinz Gröchenig

We develop the theory of frames and Parseval frames for finite-dimensional vector spaces over the binary numbers. This includes characterizations which are similar to frames and Parseval frames for real or complex Hilbert spaces, and the…

Functional Analysis · Mathematics 2009-06-19 Bernhard G. Bodmann , My Le , Letty Reza , Matthew Tobin , Mark Tomforde

Let R be a commutative ring with unity, M be an unitary R-module and {\Gamma} be a simple graph. This research article is an interplay of combinatorial and algebraic properties of M . We show a combinatorial object completely determines an…

Commutative Algebra · Mathematics 2017-11-06 Rameez Raja

We give characterizations of unital uniform topological algebras and saturated locally multiplicatively convex algebras by means of multiplicative linear functionals. Some automatic continuity theorems in advertibly complete uniform…

Functional Analysis · Mathematics 2014-01-03 M. El Azhari

In this paper we suggest new effective criteria for the density property. This enables us to give a trivial proof of the original Anders\'en-Lempert result and to establish (almost free of charge) the algebraic density property for all…

Complex Variables · Mathematics 2009-11-13 Shulim Kaliman , Frank Kutzschebauch