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We generalize the notion of a small sheaf of sets over a topological space or manifold to define the notion of a small stack of groupoids over an \'etale topological or differentiable stack. We then provide a construction analogous to the…

Algebraic Topology · Mathematics 2012-03-28 David Carchedi

In this article, the theory of sheaves is studied from a categorical point of view. This perspective vastly generalizes the usual theory of sheaves of sets to a more abstract setting which allows us to investigate the theory of sheaves with…

Commutative Algebra · Mathematics 2017-09-22 Abolfazl Tarizadeh

This paper is the first in a series of papers in which we define and study a category of "sheaves of $\mathcal Z$-modules on the set of alcoves" that carries important information on the category of representations of semisimple Lie…

Representation Theory · Mathematics 2017-01-16 Peter Fiebig , Martina Lanini

We introduce and develop the theory of metric sheaves. A metric sheaf $\A$ is defined on a topological space $X$ such that each fiber is a metric model. We describe the construction of the generic model as the quotient space of the sheaf…

Logic · Mathematics 2012-04-06 Maicol A. Ochoa , Andrés Villaveces

We introduce new foundations for relative topos theory based on stacks. One of the central results in our theory is an adjunction between the category of toposes over the topos of sheaves on a given site $({\mathcal{C}}, J)$ and that of…

Algebraic Geometry · Mathematics 2021-07-12 Olivia Caramello , Riccardo Zanfa

The category of coherent sheaves over a noetherian scheme is very important for studying the properties of a given scheme. For noetherian schemes it is a well-known fact that the topology can be fully recovered from the corresponding…

Algebraic Geometry · Mathematics 2025-07-08 Ron Held

We propose a construction of a stable category for any pretorsion theory in a lextensive category. We prove the universal property of the stable category, that extends previous results obtained for the stable category of internal preorders…

Category Theory · Mathematics 2023-01-16 Francis Borceux , Federico Campanini , Marino Gran

A brief synopsis of recent conceptions and results, the current status and future outlook of our research program of applying sheaf and topos-theoretic ideas to quantum gravity and quantum logic is presented.

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ioannis Raptis

We present a uniform theory of constructible sheaves on arbitrary schemes with coefficients in topological or even condensed rings. This is accomplished by defining lisse sheaves to be the dualizable objects in the derived infinity-category…

Algebraic Geometry · Mathematics 2023-05-30 Tamir Hemo , Timo Richarz , Jakob Scholbach

Sheaves are objects of a local nature: a global section is determined by how it looks locally. Hence, a sheaf cannot describe mathematical structures which contain global or nonlocal geometric information. To fill this gap, we introduce the…

Category Theory · Mathematics 2016-10-26 Cecilia Flori , Tobias Fritz

We define the notion of a sheaf over a complex of groups. As an application, we give a criterion for the developability of a complex of groups. When the developability is witnessed by a morphism to $\mathrm{GL}(V)$ for some $V$, our…

Group Theory · Mathematics 2022-02-15 Joshua L. Faber

In type theory, an oracle may be specified abstractly by a predicate whose domain is the type of queries asked of the oracle, and whose proofs are the oracle answers. Such a specification induces an oracle modality that captures a…

Logic · Mathematics 2026-04-30 Danel Ahman , Andrej Bauer

We develop some of the foundations of affinoid pre-adic spaces without Noetherian or finiteness hypotheses. We give some explicit examples of non-adic affinoid pre-adic spaces (including a locally perfectoid one). On the positive side, we…

Number Theory · Mathematics 2015-09-15 Kevin Buzzard , Alain Verberkmoes

This paper introduces effectful toposes as an extension of the effective topos and investigates their structure relative to Lawvere-Tierney topologies. First, we formulate effectful toposes by lifting the evidenced frame, which is a…

Logic in Computer Science · Computer Science 2026-02-27 Rinta Yamada

A sheaf of modules on a site is said to be internally projective if sheaf hom with the module preserves epimorphism. In this note, we give an example showing that internally projective sheaves of abelian groups are not in general stable…

Category Theory · Mathematics 2024-09-20 David Wärn

We prove criteria for a presheaf on logarithmic schemes to be a sheaf in the full logarithmic \'etale topology and describe several situations where the structure sheaf and logarithmic structure are logarithmic \'etale sheaves. We deduce…

Algebraic Geometry · Mathematics 2023-11-10 Samouil Molcho , Jonathan Wise

We generalise sheaf models of intuitionistic logic to univalent type theory over a small category with a Grothendieck topology. We use in a crucial way that we have constructive models of univalence, that can then be relativized to any…

Logic · Mathematics 2020-07-09 Thierry Coquand , Fabian Ruch , Christian Sattler

The phrase "(co)simplicial (pre)sheaf" can be reasonably interpreted in multiple ways. In this survey we study how the various notions familiar to the author relate to one another. We end by giving some example applications of the most…

Category Theory · Mathematics 2023-06-22 Timothy Hosgood

We give a detailed and self-contained introduction to the theory of $\lambda $-toposes and prove the following: 1) A $\lambda $-separable $\lambda $-topos has enough $\lambda $-points. 2) The classifying $\lambda $-topos of a $\kappa $-site…

Category Theory · Mathematics 2025-05-16 Christian Espíndola , Kristóf Kanalas

Algorithmicists are well-aware that fast dynamic programming algorithms are very often the correct choice when computing on compositional (or even recursive) graphs. Here we initiate the study of how to generalize this folklore intuition to…

Computational Complexity · Computer Science 2023-10-05 Ernst Althaus , Benjamin Merlin Bumpus , James Fairbanks , Daniel Rosiak