Errata

After going to press, we have fixed the following mistakes:

1. In the definition of a logos, we mistakenly said that "colimits commute with finite limits" but we meant to say that they commute with pullbacks. We thank Sarah Rovner-Frydman for noticing this mistake.
2. In Remark 5.15, we used the notation for the closed immersion prior to introducing it.
3. We have fixed a few broken links in the bibliography.

The local copy linked here has the corrections implemented.