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Presheaf of Categories


A presheaf C of categories consists of the following data:

1. For every local homeomorphism f:Y->X of topological spaces X, Y, a category C(f:Y->X);

2. For every diagram f degreesg:Z->Y->X of local homeomorphisms, a functor g^(-1):C(f:Y->X)->C(f degreesg:Z->X);

3. For every diagram f degreesg degreesh:W->Z->Y->X of local homeomorphisms, an invertible natural transformation theta_(g,h):h^(-1)g^(-1)->(gh)^(-1).

PresheafofCategoriesDiagram

In addition, for every diagram

 f degreesg degreesh degreesk:T->W->Z->Y->X

of topological spaces T, W, Z, Y, and X, commutativity is required in the above diagram.


See also

Category, Category Theory, Commutative Diagram, Functor, Homeomorphism, Presheaf, Sheaf, Topological Space

This entry contributed by Christopher Stover

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References

Brylinski, J. Loop Spaces, Characteristic Classes and Geometric Quantization. Boston: Birkhäuser, 1993.

Cite this as:

Stover, Christopher. "Presheaf of Categories." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/PresheafofCategories.html

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