derived smooth geometry
Fix some scheme .
the fppf-site (over ) is the site
This appears as (de Jong, def. 27.7.1, def 27.7.6, lemma 27.7.11).
The abbreviation “fppf” is for fidèlement plat de présentation finie : faithfully flat and of finite presentation.
But notice that it is common practice, as in the above definition, to require only local finite presentability.
Chaper 27.7 in