---
date: 2022-01-17
tags: [ web/quick-notes ]
---

# 2022-01-17

Tags:
#web/quick-notes

Refs:
?

## 02:12

Processes that look like localizations (e.g. taking isomorphism classes) rarely satisfy a sheaf condition because this rarely preserves limits.

The right way to think about stacks: homotopy sheaves.


![](figures/2022-01-17_02-19-29.png)

![](figures/2022-01-17_02-20-39.png)

![](figures/2022-01-17_02-20-48.png)

Stack: a presheaf of groupoids satisfying descent.

![](figures/2022-01-17_02-23-20.png)


![](figures/2022-01-17_02-28-03.png)