The Stacks project

U ---> R

Thanks to Emre Sertoz
http://stacks.math.columbia.edu/tag/04T4#comment-2337

Whitespace changes

Spell check: words starting with d, e, f, g, D, E, F, or G

Spell check: words starting with b, c, B, or C

Whitespace changes

Whitespace changes

LaTeX: Remove useless brackets

LaTeX: \Ob

	Introduced a macro

	\def\Ob{\mathop{\rm Ob}\nolimits}

	and replaced any occurence of \text{Ob}( with \Ob(. There are
	still some occurences of \text{Ob} but these are sets, not the
	operator that takes the set of objects of a category.

LaTeX: \Sch

	Introduced a new macro

	\def\Sch{\textit{Sch}}

	and replaced all the occurences of \textit{Sch} with \Sch.

Definition of a presentation of an algebraic stack

	Plus some small local improvements.

Added new tags

2-fibre products of algebraic stacks

	This looks complicated because of or insistence that in the
	first chapter on algebraic stacks we use a notation which
	distinguishes between schemes, algebraic spaces, and algebraic
	stacks.

More cleaning up of Algebraic Stacks

	More or less OK proof of the easy direction for going between
	algebraic stacks and presentations. It would be good to add more
	material allowing us to work more easily with fibred
	categories...

Started cleaning up chapter on algebraic stacks

Splitting out different notions of representability

	Hopefully this will improve the exposition (everntually).