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We prove a conjecture of Emerton, Gee and Hellmann concerning the overconvergence of \'etale $(\varphi,\Gamma)$-modules in families parametrized by topologically finite type $\mathbb{Z}_{p}$-algebras. As a consequence, we deduce the…

Number Theory · Mathematics 2024-06-28 Gal Porat

This paper explores the interface between algebra, topology, and logic by developing the theory of sheaves and etale spaces for residuated lattices, algebraic structures central to substructural and fuzzy logics. We construct…

Logic · Mathematics 2025-07-17 Saeed Rasouli

An \'etale structure over a topological space $X$ is a continuous family of structures (in some first-order language) indexed over $X$. We give an exposition of this fundamental concept from sheaf theory and its relevance to countable model…

Logic · Mathematics 2023-10-19 Ruiyuan Chen

We introduce and study a class of algebraic stacks with finite inertia in positive and mixed characteristic, which we call tame algebraic stacks. They include tame Deligne-Mumford stacks, and are arguably better behaved than general…

Algebraic Geometry · Mathematics 2007-05-23 Dan Abramovich , Martin Olsson , Angelo Vistoli

We compute the (stable) \'etale cohomology of $\mathrm{Hom}_{n}(C, \mathcal{P}(\vec{\lambda}))$, the moduli stack of degree $n$ morphisms from a smooth projective curve $C$ to the weighted projective stack $\mathcal{P}(\vec{\lambda})$, the…

Algebraic Geometry · Mathematics 2022-07-07 Oishee Banerjee , Jun-Yong Park , Johannes Schmitt

For a toric Deligne-Mumford (DM) stack, we can consider a certain generalization of the Frobenius endomorphism. For such an endomorphism on a two-dimensional toric DM stack, we show that the push-forward of the structure sheaf generates the…

Algebraic Geometry · Mathematics 2013-06-18 Ryo Ohkawa , Hokuto Uehara

Using Nisnevich coverings and a Hilbert stack of stacky points, we prove \'etale d\'evissage results for non-representable \'etale and quasi-finite flat coverings. We give applications to absolute noetherian approximation of algebraic…

Algebraic Geometry · Mathematics 2019-05-07 Jack Hall , David Rydh

Derived mapping stacks are a fundamental source of examples of derived enhancements of classical moduli problems. For instance, they appear naturally in Gromov-Witten theory and in some branches of geometric representation theory. In this…

Algebraic Geometry · Mathematics 2018-12-24 Julian Holstein , Mauro Porta

We define a tricategory T of length 3 complexes of abelian sheaves, whose hom-bigroupoids consist of weak morphisms of such complexes. We also define a 3-category 2PIC(S) of Picard 2-stacks, whose hom-2-groupoids consist of additive…

Algebraic Geometry · Mathematics 2014-01-29 A. Emin Tatar

We extend the notion of algebraic stack to an arbitrary subcanonical site C. If the topology on C is local on the target and satisfies descent for morphisms, we show that algebraic stacks are precisely those which are weakly equivalent to…

Algebraic Topology · Mathematics 2007-08-21 Sharon Hollander

Let $\mathcal{G}$ be a bundle gerbe with connection on a smooth manifold $M$, and let $\rho: G \rightarrow \operatorname{Diff}(M)$ be a smooth action of a Fr\'echet--Lie group $G$ on $M$ that preserves the isomorphism class of…

Differential Geometry · Mathematics 2024-01-25 Bas Janssens , Peter Kristel

Through the subsequent discussion we consider a certain particular sort of (topological) algebras, which may substitute the `` structure sheaf algebras'' in many--in point of fact, in all--the situations of a geometrical character that…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Anastasios Mallios

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

We generalize the construction of a moduli space of semistable pairs parametrizing isomorphism classes of morphisms from a fixed coherent sheaf to any sheaf with fixed Hilbert polynomial under a notion of stability to the case of projective…

Algebraic Geometry · Mathematics 2024-04-09 Yijie Lin

We introduce differentiable stacks and explain the relationship with Lie groupoids. Then we study $S^1$-bundles and $S^1$-gerbes over differentiable stacks. In particular, we establish the relationship between $S^1$-gerbes and groupoid…

Differential Geometry · Mathematics 2009-01-02 Kai Behrend , Ping Xu

This work deals with the topological classification of germs of singular foliations on $(\mathbb C^{2},0)$. Working in a suitable class of foliations we fix the topological invariants given by the separatrix set, the Camacho-Sad indices and…

Dynamical Systems · Mathematics 2017-09-19 David Marín , Jean-François Mattei , Éliane Salem

In this paper, we construct in characteristic zero a derived foliation on derived mapping stacks $\underline{\mathbf{Map}}_S(X,Y)$, for $S$ a base derived stack, $X$ a proper schematic, flat, and local complete intersection derived stack…

Algebraic Geometry · Mathematics 2025-11-07 Victor Alfieri

The representability theorem for stacks, due to Artin in the underived setting and Lurie in the derived setting, gives conditions under which a stack is representable by an $n$-geometric stack. In recent work of Ben-Bassat, Kelly, and…

Algebraic Geometry · Mathematics 2025-11-17 Rhiannon Savage

We consider orbifolds as diffeological spaces. This gives rise to a natural notion of differentiable maps between orbifolds, making them into a subcategory of diffeology. We prove that the diffeological approach to orbifolds is equivalent…

Differential Geometry · Mathematics 2010-04-16 Patrick Iglesias , Yael Karshon , Moshe Zadka

Motivated by localization theorems on moduli spaces, we prove a structural classification of Deligne-Mumford stacks with an action of a torus where the induced action on the coarse moduli space is trivial. We also establish a general local…

Algebraic Geometry · Mathematics 2024-02-19 Jarod Alper , Felix Janda