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We take a new look at dilation theory for nonself-adjoint operator algebras. Among the extremal (co)extensions of a representation, there is a special property of being fully extremal. This allows a refinement of some of the classical…

Operator Algebras · Mathematics 2011-09-02 Kenneth R. Davidson , Elias G. Katsoulis

In generalization of knot quandles we introduce similar algebraic structures associated with arbitrary pairs consisting of a path-connected topological space and its path-connected subspace.

Geometric Topology · Mathematics 2022-05-16 Vladimir Turaev

We study the modular representation theory of the symmetric and alternating groups. One of the most natural ways to label the irreducible representations of a given group or algebra in the modular case is to show the unitriangularity of the…

Representation Theory · Mathematics 2020-12-09 Olivier Brunat , Jean-Baptiste Gramain , Nicolas Jacon

The purpose of this paper is to introduce and investigate the notion of derivation for quandle algebras. More precisely, we describe the symmetries on structure constants providing a characterization for a linear map to be a derivation. We…

Rings and Algebras · Mathematics 2021-06-24 M. Elhamdadi , A. Makhlouf , S. Silvestrov , E. Zappala

A hypermap is an embedding of a connected hypergraph into an orientable closed surface. A covering between hypermaps is a homomorphism between the embedded hypergraphs which extends to an orientation-preserving covering of the supporting…

Combinatorics · Mathematics 2018-06-13 Na-Er Wang , Kan Hu

The goal of this paper is to make a surprising connection between several central conjectures in algebraic geometry: the Nonvanishing Conjecture, the Abundance Conjecture, and the Semiampleness Conjecture for nef line bundles on K-trivial…

Algebraic Geometry · Mathematics 2020-04-07 Vladimir Lazić , Thomas Peternell

In this paper, we present a constructive generalization of metric and uniform spaces by introducing a new class of spaces, called cover spaces. These spaces form a topological concrete category with a full reflective subcategory of complete…

General Topology · Mathematics 2024-12-31 Valery Isaev

The main goal of the paper is to prove the existence of the universal cover for $RCD^*(K,N)$-spaces. This generalizes earlier work of C. Sormani and the second named author on the existence of universal covers for Ricci limit spaces. As a…

Metric Geometry · Mathematics 2020-04-22 Andrea Mondino , Guofang Wei

We realize the crystal associated to the quantized enveloping algebras with a symmetric generalized Cartan matrix as a set of Lagrangian subvarieties of the cotangent bundle of the quiver variety. As a by-product, we give a counterexample…

q-alg · Mathematics 2015-12-22 Masaki Kashiwara , Yoshihisa Saito

Projective spaces for finite-dimensional vector spaces over general fields are considered. The geometry of these spaces and the theory of line bundles over these spaces is presented. Particularly, the space of global regular sections of…

Algebraic Geometry · Mathematics 2023-09-21 Andrew D. Lewis

The quotient-cusp singularities are isolated complex surface singularities that are double-covered by cusp singularities. We show that the universal abelian cover of such a singularity, branched only at the singular point, is a complete…

Algebraic Geometry · Mathematics 2007-05-23 Walter D. Neumann , Jonathan Wahl

A finite-dimensional unital and associative algebra over $\mathbb{R}$, or what we shall call simply "an algebra" in this paper for short, generalities the construction by which we derive the complex numbers by "adjoining an element $i$" to…

Rings and Algebras · Mathematics 2017-08-04 Nathan BeDell

We investigate the classification of topological quandles on some simple manifolds. Precisely we classify all Alexander quandle structures, up to isomorphism, on the real line and the unit circle. For the closed unit interval $[0, 1]$, we…

Geometric Topology · Mathematics 2019-07-25 Zhiyun Cheng , Mohamed Elhamdadi , Boris Shekhtman

The aim of this paper is to provide a new characterization of isomorphism classes of generalized Alexander quandles in terms of the underlying groups and their automorphisms. This extends the previous result [4, Theorem 1.4]. Additionally,…

Geometric Topology · Mathematics 2024-06-04 Akihiro Higashitani , Seiichi Kamada , Jin Kosaka , Hirotake Kurihara

In order to be able to use methods of Universal Algebra for investigating posets, we assign to every pseudocomplemented poset, to every relatively pseudocomplemented poset and to every sectionally pseudocomplemented poset a certain algebra…

Rings and Algebras · Mathematics 2021-03-24 Ivan Chajda , Helmut Länger

We develop the framework for augmented homotopical algebraic geometry. This is an extension of homotopical algebraic geometry, which itself is a homotopification of classical algebraic geometry. To do so, we define the notion of…

Algebraic Geometry · Mathematics 2017-11-08 Scott Balchin

We study generalized splines from the perspective of the representation theory of the category of graphs with contractions. Our main theorem proves a kind of finite generation, which in turn implies the existence of a ``universal generating…

Combinatorics · Mathematics 2026-05-26 Jacob Matherne , Eric Ramos , Julianna Tymoczko

We study the homeomorphism types of certain covers of (always orientable) surfaces, usually of infinite-type. We show that every surface with non-abelian fundamental group is covered by every noncompact surface, we identify the universal…

Geometric Topology · Mathematics 2025-08-05 Ian Biringer , Yassin Chandran , Tommaso Cremaschi , Jing Tao , Nicholas G. Vlamis , Mujie Wang , Brandis Whitfield

We present constructive versions of Krull's dimension theory for commutative rings and distributive lattices. The foundations of these constructive versions are due to Joyal, Espan\~ol and the authors. We show that this gives a constructive…

Commutative Algebra · Mathematics 2017-12-14 Thierry Coquand , Henri Lombardi

Further to the functional representations of C$^*$-algebras proposed by R. Cirelli, A. Mania and L. Pizzocchero, we consider in this article the uniform K\"ahler bundle (in short, UKB) description of some C$^*$-algebraic subjects. In…

Operator Algebras · Mathematics 2015-09-10 Xiao Chen
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