# nLab geometry

geometry $\leftarrow$ Isbell duality $\rightarrow$ algebra

## Theorems

See also topology.

There are many entries on sheaf, stack, site, locale and topos theory including

and pages on various cohomologies, including sheaf cohomology, nonabelian cohomology, differential cohomology, Deligne cohomology, etale cohomology, equivariant cohomology, Bredon cohomology and their cocycle classes including torsors, gerbes, principal 2-bundles as well as the related picture of the descent theory (cf. oriental, descent for simplicial presheaves…). A modern systematic theory of cohomology and descent can be done using the language of $(\infinity,1)$-categories and abstract homotopy theory, say via Quillen model categories (e.g. of simplicial presheaves).

duality between algebra and geometry in physics:

Revised on September 15, 2015 14:30:03 by Urs Schreiber (147.231.89.106)