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Seminar on Stacks and Groupoids
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\begin{Huge}\textsc{The isomorphism presheaf and the}
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\begin{Huge}\textsc{definition of a stack}
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\begin{Large}\textbf{
 Sebastian Casalaina-Martin}
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University of Colorado at Boulder
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In this lecture we will introduce the isomorphism presheaf; this is a presheaf  associated to a pair of objects of a category fibered in groupoids over a site, lying over the same object in the base category.  The sheaf condition determines whether isomorphisms of the two chosen objects can be glued together (uniquely) from isomorphisms obtained after a pull-back.  With this definition, we will be able to define a stack.


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Tuesday March 30, 2010

4:00 p.m.

MATH 350

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