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Search options not deleted user 118688
20 votes
7 answers
3k views

What are the occurrences of stacks outside algebraic geometry, differential geometry, and ge...

What are the occurrences of the notion of a stack outside algebraic geometry, differential geometry, and general topology? In most of the references, the introduction of the notion of a stack takes …
Praphulla Koushik's user avatar
5 votes
1 answer
362 views

K-theory for a (geometric) stack

There is a notion of $K$-theory for a manifold $M$. Is there a notion of $K$-theory for a stack $\mathcal{D}\rightarrow \text{Man}$ that is representable by a Lie groupoid $\mathcal{G}$; that is …
Praphulla Koushik's user avatar
4 votes
1 answer
551 views

Stack being represented by a scheme/manifold

On page $10$ of the survey article Algebraic stacks, by T. Gomez (arXiv:math/9911199), we have following result If a stack has an object with an automorphism other than the identity, then the sta …
Praphulla Koushik's user avatar
4 votes
0 answers
271 views

connection on principal bundles over algebraic/geometric stacks

Is there a notion of connection on a principal bundle over an algebraic or geometric stack? By a geometric stack, I mean a stack over category of manifolds that is representable by a Lie groupoid; t …
Praphulla Koushik's user avatar
4 votes
0 answers
286 views

MSRI Workshop videos and lecture notes

I am referring to MSRI workshop "Introductory Workshop on Algebraic Stacks, Intersection Theory, and Non-Abelian Hodge Theory". There are videos and lecture notes available which can be seen on click …
Praphulla Koushik's user avatar
4 votes
0 answers
1k views

English translation of G.Laumon, L.Moret-Bailly book Champs algébriques

Is there an English translation of G.Laumon, L.Moret-Bailly book Champs algébriques. Most questions on this site on stacks received this book as reference in comments/answers. So, I want to ask if …
Praphulla Koushik's user avatar
3 votes
0 answers
460 views

Prerequisites for understanding algebraic geometry of “algebraic gerbes”

I am trying to learn about algebraic geometry of gerbes. I am familiar with set up of gerbes in the case of differential geometry. Though there is some similarity between differentiable gerbes and ge …
Praphulla Koushik's user avatar
2 votes
0 answers
340 views

Notions of algebraic/differential geometry of scheme/manifolds extended to algebraic/differe...

Given a manifold, one can associate a stack over the category of manifolds, which is a differential geometric stack. This gives a functor $\text{Man}\rightarrow \text{D.Stacks}$. This is an embedding …
Praphulla Koushik's user avatar
2 votes
1 answer
540 views

Stack associated to Groupoid object in category $\text{Sch}/S$

Consider the category of manifolds $\text{Man}$. A groupoid object in the category of manifolds is called a Lie groupoid, denoted by $\mathcal{G}$. There is a way to associate a stack (over the cate …
Praphulla Koushik's user avatar
1 vote

Representaility of morphism of stacks for schemes

This is not an answer, just too long for a comment. So, writing as an answer. It turns out that, one may not be able to see the correspondence between these three definitions as one of them is stated …
Praphulla Koushik's user avatar
0 votes

A presentation of an algebraic stack is epi. in etale topology

A "similar" result along with proof can be found as Lemma 2.14 of Differentiable Stacks and Gerbes. I would like to give more details if you want.
Praphulla Koushik's user avatar