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The notion of a tamely ramified covering is canonical only for curves. Several notions of tameness for coverings of higher dimensional schemes have been used in the literature. We show that all these definitions are essentially equivalent.…

Algebraic Geometry · Mathematics 2009-08-11 Moritz Kerz , Alexander Schmidt

We consider pairs (X,Y) where X is a compact, locally CAT(-1) space, and Y is a totally geodesic subspace. The inclusion induces an embedding of the boundaries at infinity of the universal covers; we focus on the case where these are…

Geometric Topology · Mathematics 2008-11-10 F. T. Farrell , J. -F. Lafont

We prove that any map between projection lattices of $AW^\ast$-algebras $A$ and $B$, where $A$ has no Type $I_2$ direct summand, that preserves orthocomplementation and suprema of arbitrary elements, is a restriction of a normal Jordan…

Operator Algebras · Mathematics 2014-08-21 Jan Hamhalter

We define nodal finite dimensional algebras and describe their structure over an algebraically closed field. For a special class of such algebras (type A) we find a criterion of tameness.

Representation Theory · Mathematics 2015-01-27 Yuriy A. Drozd , Vasyl V. Zembyk

We show that if a complex has free finitely generated reduced homology groups for two consecutive dimensions and trivial homology for all other dimensions, then it must have the homotopy type of a wedge of spheres of two consecutive…

Algebraic Topology · Mathematics 2025-03-14 Omar Antolín Camarena , Andrés Carnero Bravo

Let $K$ be an algebraically closed field with $\operatorname{char}(K)\neq 2$, and $A$ a skewed-gentle $K$-algebra. In this case, Crawley-Boevey's description of the indecomposable $A$-modules becomes particularly easy. This allows us to…

Representation Theory · Mathematics 2025-10-20 Christof Geiß

In the area of Tame Geometry, different model-theoretic tameness conditions are established and their relationships are analyzed. We construct a subfield $K$ of the real numbers that lacks several of such tameness properties. As our main…

Logic · Mathematics 2025-07-01 Lothar Sebastian Krapp , Matthieu Vermeil , Laura Wirth

The assumption that an AEC is tame is a powerful assumption permitting development of stability theory for AECs with the amalgamation property. Lately several upward categoricity theorems were discovered where tameness replaces strong…

Logic · Mathematics 2007-05-23 Rami Grossberg , Alexei S. Kolesnikov

We establish a relative version of the abstract "affine representability" theorem in ${\mathbb A}^1$--homotopy theory from Part I of this paper. We then prove some ${\mathbb A}^1$--invariance statements for generically trivial torsors under…

Algebraic Geometry · Mathematics 2018-03-16 Aravind Asok , Marc Hoyois , Matthias Wendt

We study Popa's notion of rigidity for equivalence relations induced by actions on homogeneous spaces. For any lattices $\Gamma,\Lambda$ in a semisimple Lie group $G$ with finite center and no compact factors we prove that the action…

Dynamical Systems · Mathematics 2010-11-05 Adrian Ioana , Yehuda Shalom

We prove that the local (pseudo)group of biholomorphisms stabilizing a minimal, finitely nondegenerate real algebraic submanifold in C^n is a real algebraic local Lie group (the works of S.M. Baouendi, P. Ebenfelt, L.-P. Rothschild and D.…

Complex Variables · Mathematics 2007-05-23 Herve Gaussier , Joel Merker

We show that the infinite symmetric product of a connected graded-commutative algebra over the rationals is naturally isomorphic to the free graded-commutative algebra on the positive degree subspace of the original algebra. In particular,…

Rings and Algebras · Mathematics 2021-11-09 Jiahao Hu , Aleksandar Milivojević

We prove a density version of the Halpern-L\"{a}uchli Theorem. This settles in the affirmative a conjecture of R. Laver. Specifically, let us say that a tree $T$ is homogeneous if $T$ has a unique root and there exists an integer $b\meg 2$…

Combinatorics · Mathematics 2014-10-23 Pandelis Dodos , Vassilis Kanellopoulos , Nikolaos Karagiannis

In topological dynamics, tame and null systems arise naturally in the study of low-complexity aperiodic behaviour, yet providing concrete and easily testable conditions to establish their existence in a canonical class of systems is often…

Dynamical Systems · Mathematics 2026-03-04 Maik Gröger , Elżbieta Krawczyk

For an Artinian $(n-1)$-Auslander algebra $\Lambda$ with global dimension $n(\geq 2)$, we show that if $\Lambda$ admits a trivial maximal $(n-1)$-orthogonal subcategory of $\mod\Lambda$, then $\Lambda$ is a Nakayama algebra and the…

Representation Theory · Mathematics 2009-03-24 Zhaoyong Huang , Xiaojin Zhang

We prove two structure theorems for simple, locally finite dimensional Lie algebras over an algebraically closed field of characteristic $p$ which give sufficient conditions for the algebras to be of the form $[R^{(-)}, R^{(-)}] / (Z(R)…

Rings and Algebras · Mathematics 2013-11-22 Johanna Hennig

We prove a theorem which gives a bijection between the support $\tau$-tilting modules over a given finite-dimensional algebra $A$ and the support $\tau$-tilting modules over $A/I$, where $I$ is the ideal generated by the intersection of the…

Representation Theory · Mathematics 2020-03-26 Florian Eisele , Geoffrey Janssens , Theo Raedschelders

We introduce the notion of a w-good $\lambda$-frame which is a weakening of Shelah's notion of a good $\lambda$-frame. Existence of a w-good $\lambda$-frame implies existence of a model of size $\lambda^{++}$. Tameness and amalgamation…

Logic · Mathematics 2018-03-13 Marcos Mazari Armida

We prove an abstract compactness theorem for a family of generalized Seiberg-Witten equations in dimension three. This result recovers Taubes' compactness theorem for stable flat $\mathbf{P}\mathrm{SL}_2(\mathbf{C})$-connections as well as…

Differential Geometry · Mathematics 2022-02-02 Thomas Walpuski , Boyu Zhang

For any truncated path algebra $\Lambda$ of a quiver, we classify, by way of representation-theoretic invariants, the irreducible components of the parametrizing varieties $\mathbf{Rep}_{\mathbf{d}}(\Lambda)$ of the $\Lambda$-modules with…

Representation Theory · Mathematics 2019-12-20 K. R. Goodearl , B. Huisgen-Zimmermann