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We show that the tame \'etale fundamental group of a connected normal finite type separated scheme remains invariant upon base change between algebraically closed fields of characteristic $p \geq 0$.

Algebraic Geometry · Mathematics 2024-01-24 Aaron Landesman

There is a well-known stratification of the moduli space $M_g$ of Deligne-Mumford stable curves of genus $g$ by the loci of stable curves with a fixed number $i$ of nodes, where $i \le 3g-3$. The associated moduli stack ${\cal M}_g$ admits…

Algebraic Geometry · Mathematics 2007-05-23 Joerg Zintl

We introduce the extra slow Tamari lattices, a new family of lattices defined on faithfully balanced tableaux. These tableaux arise naturally from the representation theory of type \( A \) quivers, and our construction extends the classical…

Combinatorics · Mathematics 2026-05-21 Sylvie Corteel , Jihyeug Jang , Baptiste Rognerud

We prove that the free product of two finitely presented locally tame groups is locally tame and describe many examples of tame subgroups of finitely presented groups. We also include some open problems related to tame subgroups.

Group Theory · Mathematics 2017-11-03 Rita Gitik

We explain how to define an embedding of a tame stack over a noetherian ring into a certain generalization of a weighted projective stack using a notion of ample vector bundle on the stack. As applications we construct algebraic moduli…

Algebraic Geometry · Mathematics 2024-07-03 Daniel Bragg , Martin Olsson , Rachel Webb

We classify tame block algebras of Hecke algebras of classical type over an algebraically closed field of odd characteristic.

Representation Theory · Mathematics 2023-06-22 Susumu Ariki

These are notes on derived algebraic geometry in the context of animated rings. More precisely, we recall the proof of To\"en-Vaqui\'e that the derived stack of perfect complexes is locally geometric in the language of $\infty$-categories.…

Algebraic Geometry · Mathematics 2022-08-03 Can Yaylali

The stable reduction theorem of Deligne and Mumford --- The moduli space of smooth projective curves of genus $g$ is a quasi-projective algebraic variety, but is not projective. To understand its geometry, it may be crucial to consider…

Algebraic Geometry · Mathematics 2019-04-16 Antoine Chambert-Loir

A finite \'etale map between irreducible, normal varieties is called tame, if it is tamely ramified with respect to all partial compactifications whose boundary is the support of a strict normal crossings divisor. We prove that if the…

Algebraic Geometry · Mathematics 2016-06-29 Lars Kindler

We explore the integration of representations from a Lie algebra to its algebraic group in positive characteristic. An integrable module is stable under the twists by group elements. Our aim is to investigate cohomological obstructions for…

Representation Theory · Mathematics 2019-10-30 Dmitriy Rumynin , Matthew Westaway

An old theorem of Charney and Lee says that the classifying space of the category of stable nodal topological surfaces and isotopy classes of degenerations has the same rational homology as the Deligne-Mumford compactification. We give an…

Algebraic Topology · Mathematics 2014-10-01 Johannes Ebert , Jeffrey Giansiracusa

Based on the methods used by the author to prove the Riemann-Roch formula for algebraic stacks, this paper contains a description of the rationnal G-theory of Deligne-Mumford stacks over general bases. We will use these results to study…

Algebraic Geometry · Mathematics 2007-05-23 B. Toen

We describe a new approach to the definition of the moduli functor of stable varieties. While there is wide agreement as to what classes of varieties should appear, the notion of a family of stable surfaces is quite subtle, as key numerical…

Algebraic Geometry · Mathematics 2009-04-21 Dan Abramovich , Brendan Hassett

We initiate the axiomatic study of affine oriented matroids (AOMs) on arbitrary ground sets, obtaining fundamental notions such as minors, reorientations and a natural embedding into the frame work of Complexes of Oriented Matroids. The…

Combinatorics · Mathematics 2024-04-09 Emanuele Delucchi , Kolja Knauer

We prove that the homotopy algebraic K-theory of tame quasi-DM stacks satisfies cdh-descent. We apply this descent result to prove that if X is a Noetherian tame quasi-DM stack and i < -dim(X), then K_i(X)[1/n] = 0 (resp. K_i(X, Z/n) = 0)…

K-Theory and Homology · Mathematics 2019-12-18 Marc Hoyois , Amalendu Krishna

We prove that any $\tau$-tilting finite incidence algebra of a finite poset is representation-finite, and that any $\mathbf{g}$-tame incidence algebra of a finite simply connected poset is tame. As the converse of these assertions are known…

Representation Theory · Mathematics 2025-07-31 Erlend D. Børve , Jacob Fjeld Grevstad , Endre S. Rundsveen

Thin sums matroids were introduced to extend the notion of representability to non-finitary matroids. We give a new criterion for testing when the thin sums construction gives a matroid. We show that thin sums matroids over thin families…

Combinatorics · Mathematics 2012-04-30 Hadi Afzali , Nathan Bowler

In this paper we determine the derived representation type of quadratic string algebras and we prove that every derived tame quadratic string algebra whose quiver has cycles is derived equivalent to some skewed-gentle algebra.

Representation Theory · Mathematics 2020-11-17 Marlon Pimenta Fonseca

This is the first paper in a series on intrinsic Donaldson-Thomas theory, where we develop a new framework for enumerative geometry that allows the generalization of constructions and results from linear moduli stacks to general non-linear…

Algebraic Geometry · Mathematics 2025-09-12 Chenjing Bu , Daniel Halpern-Leistner , Andrés Ibáñez Núñez , Tasuki Kinjo

We connect the homotopy type of simplicial moduli spaces of algebraic structures to the cohomology of their deformation complexes. Then we prove that under several assumptions, mapping spaces of algebras over a monad in an appropriate…

Algebraic Topology · Mathematics 2015-07-20 Sinan Yalin