The Stacks project

Add some internal references in morphisms

Thanks to Jonas Ehrhard
https://stacks.math.columbia.edu/tag/01UA#comment-6456

Topology + Morphisms: Fix error in topology lemma + fallout

	The error was in thinking that generalizations lift along any
	open map of topological spaces, which they do not. An example
	can be constructed relatively easily.

	It turns out that we never used this anywhere in the rest of the
	chapters, which is a lucky break. We fixed a comment about this
	in the chapter on morphisms of schemes to be a little more
	clear, and we added a lemma stating explicitly that
	generalizations do lift along flat morphisms of schemes.

Started tags infrastructure

	new file:   scripts/add_tags.py
	modified:   scripts/functions.py
	new file:   tags/initial_tags
	new file:   tags/tags

Switched sections again

	modified:   algebra.tex
	modified:   morphisms.tex

Soul searching on choice defintions in topologies

	modified:   categories.tex
	modified:   etale.tex
	modified:   morphisms.tex
	modified:   sets.tex
	modified:   sites.tex
	modified:   stacks-git.htm

More stuff added

	modified:   algebra.tex
	modified:   etale.tex
	modified:   morphisms.tex
	modified:   my.bib
	modified:   properties.tex
	modified:   schemes.tex
	modified:   sets.tex
	modified:   topology.tex