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Let $\mathcal{A}$ be a separable nuclear C*-algebra, and $\mathcal{B}$ be a nonunital separable simple $\mathcal{Z}$-stable C*-algebra. Continuing the work from Gabe-Lin-Ng, we classify all essential extensions, with large complement, of…

Operator Algebras · Mathematics 2026-02-25 Ping Wong Ng , Cangyuan Wang

Let $N$ and $H$ be groups, and let $G$ be an extension of $H$ by $N$. In this article we describe the structure of the complex group ring of $G$ in terms of data associated with $N$ and $H$. In particular, we present conditions on the…

Rings and Algebras · Mathematics 2022-03-01 Johan Öinert , Stefan Wagner

In this paper, we introduce the monomial arrow removal operation for bound quiver algebras, and show that it is a novel reduction technique for determining the finiteness of the finitistic dimension. Our approach first develops a general…

Representation Theory · Mathematics 2025-07-31 Karin Erdmann , Odysseas Giatagantzidis , Chrysostomos Psaroudakis , Øyvind Solberg

We revisit the concept of special algebras, also known as \textit{purely inseparable ring extensions}. This concept extends the notion of purely inseparable field extensions to the more general context of extensions of commutative rings. We…

Commutative Algebra · Mathematics 2024-10-08 Celia del Buey de Andrés , Diego Sulca

We introduce the notions of $\tau$-exceptional and signed $\tau$-exceptional sequences for any finite dimensional algebra. We prove that for a fixed algebra of rank $n$, and for any positive integer $t \leq n$, there is a bijection between…

Representation Theory · Mathematics 2021-06-04 Aslak Bakke Buan , Bethany Marsh

Given an abelian, CM extension K of any totally real number field k, we consider two conjectures `of Stark type'. The `Integrality Conjecture' concerns the image of a p-adic map `\mathfrak{s}_{K/k,S}' determined by the minus-part of the…

Number Theory · Mathematics 2008-07-10 David Solomon

We prove that if A is a finite algebra with a parallelogram term that satisfies the split centralizer condition, then A is dualizable. This yields yet another proof of the dualizability of any finite algebra with a near unanimity term, but…

Rings and Algebras · Mathematics 2016-01-01 Keith A. Kearnes , Agnes Szendrei

We prove that all bounded subsets of $\mathbb{Q}_p^n$ containing a line segment of unit length in every direction have Hausdorff and Minkowski dimension $n$. This is the analogue of the classical Kakeya conjecture with $\mathbb{R}$ replaced…

Number Theory · Mathematics 2021-11-02 Bodan Arsovski

Let $A$ be an amenable separable \CA and $B$ be a non-unital but $\sigma$-unital simple \CA with continuous scale. We show that two essential extensions $\tau_1$ and $\tau_2$ of $A$ by $B$ are approximately unitarily equivalent if and only…

Operator Algebras · Mathematics 2007-05-23 Huaxin Lin

In this short paper we prove that a finite dimensional algebra is hereditary if and only if there is no loop in its ordinary quiver and every $\tau$-tilting module is tilting.

Representation Theory · Mathematics 2015-07-10 Yichao Yang , Jinde Xu

We prove that a polynomial map is invertible if and only if some associated differential ring homomorphism is bijective. To this end, we use a theorem of Crespo and Hajto linking the invertibility of polynomial maps with Picard-Vessiot…

Algebraic Geometry · Mathematics 2019-05-06 Elzbieta Adamus , Teresa Crespo , Zbigniew Hajto

The Jacobian Conjecture has been reduced to the symmetric homogeneous case. In this paper we give an inversion formula for the symmetric case and relate it to a combinatoric structure called the Grossman-Larson Algebra. We use these tools…

Combinatorics · Mathematics 2007-05-23 David Wright

We establish a criterion for when an abelian extension of infinite-dimensional Lie algebras integrates to a corresponding Lie group extension $\hat{G}$ of $G$ by $A$, where $G$ is a connected, simply connected Lie group and $A$ is a…

Differential Geometry · Mathematics 2012-03-12 Pedram Hekmati

Artin's conjecture is established for all forms that can be realised as a diagonal form on an hyperplane.

Number Theory · Mathematics 2018-06-14 Jörg Brüdern , Olivier Robert

In this paper, we study the double extension of a restricted quadratic Hom-Lie algebra $(V,[\cdot,\cdot]_{V},\alpha_{V},B_{V})$, which is an enlargement of $V$ by means of a central extension and a restricted derivation $\mathscr{D}$. In…

Rings and Algebras · Mathematics 2024-01-18 Dan Mao , Zeyu Hao , Liangyun Chen

An algebraic extension K of the rationals has the Bogomolov property if the absolute logarithmic height of non-torsion points of K* is bounded away from 0. We define a relative extension L/K to be Bogomolov if this holds for points of L\K.…

Number Theory · Mathematics 2017-05-09 Robert Grizzard

Let $A$ be a $C^*$-algebra. We say that $A$ satisfies the SP if every bounded homomorphism $A\to B(K)$, with $K$ a Hilbert space, is similar to a $*$-homomorphism. We introduce three hypotheses that relate to extending hyperreflexive…

Operator Algebras · Mathematics 2025-11-20 G. K. Eleftherakis , V. I. Paulsen

We show that for any uniformly parabolic fully nonlinear second-order equation with bounded measurable "coefficients" and bounded "free" term in the whole space or in any cylindrical smooth domain with smooth boundary data one can find an…

Analysis of PDEs · Mathematics 2013-06-11 N. V. Krylov

For finite dimensional algebras over algebraically closed fields, we study the sets of pairwise Hom-orthogonal modules and obtain new results on some open conjectures on the behaviour of bricks and several related problems, which we…

Representation Theory · Mathematics 2025-02-18 Kaveh Mousavand , Charles Paquette

Let $L/K$ be a finite Galois extension of local fields. The Hasse-Arf theorem says that if Gal$(L/K)$ is abelian then the upper ramification breaks of $L/K$ must be integers. We prove the following converse to the Hasse-Arf theorem: Let $G$…

Number Theory · Mathematics 2023-02-02 G. Griffith Elder , Kevin Keating