[darcs-users] How to extend a patch theory to fully commute

[James Cook]

On Wed, 1 Jul 2020 at 10:21, Ben Franksen <ben.franksen at online.de> wrote:
> Am 01.07.20 um 05:09 schrieb James Cook:
> > The context address /points to/ a context c if there exists a
> > permutation of (Qi) such that all the patches with names in X come
> > before patches with names in Y, and c is the after-context of the k-th
> > patch in the sequence (equivalently, the before-context of the (k+1)-th
> > patch), where k = |X|.
>
> and later:
>
> > Definition: A context address (a, b, (Qi), X, Y) is /minimal/ if it is
> > impossible (in the primitive patch theory) to commute the sequence (Qi)
> > so that it begins with a patch in X or ends with a patch in Y.
>
> Did you mix up X and Y here? I would have expected the sentence to say
> "begins with a patch in Y or ends with a patch in X".

I think this part is correct as written. I added some more
explanation: https://hub.darcs.net/falsifian/misc-pub/patch/3bf868962261b8b275f81a82136106ee4c444dd1

The point of minimal addresses is that they "point" to contexts that
aren't already part of the primitive patch theory. If a patch in X
could be moved to the start, or a patch in Y could be moved to the
end, then the address could be made even more minimal by leaving out
that patch (the more minimal address would be called a
"simplification" as defined in Chapter 4).

James