Write-up on "tree repositories" as an alternative to conflictors

I wrote a description of how to store a repository as a tree of
primitive patches with active and inactive branches, as an alternative
to conflictors. For context, see recent discussion on the thread
"How to extend a patch theory to fully commute".

It is Section 4 of this pdf: https://www.falsifian.org/a/xxOw/misc.pdf
(I decided to add it to the end of the last pdf I sent to this list,
but you can pretty much ignore the previous sections.)

The tex source is at
https://hub.darcs.net/falsifian/misc-pub/browse/patch_theory/misc.tex .
I tagged this version as "2020-11-24_tree_repositories" but may push
corrections.

The write-up is pretty long. Part of that is because I put a long
examples and motivation section at the start (Section 4.1); hopefully
that at least should be easy to get through. Another reason is that my
attempt in Section 4.2.11 to show you can view a "tree repository" as a
set of "tree patches", in order to retain some of the advantages of "a
repository is a set of patches" as in Darcs, turned out to be fairly
complicated. I'm not completely satisfied with that section and listed
a bunch of caveats at the end.

-- 
James