X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=topbloke-formulae.git;a=blobdiff_plain;f=strategy.tex;h=a4716b313dd577c5e74c6e1a7afe4f39ba8be082;hp=c870cfbcfe4f77ecf430531d585f51712146076f;hb=f4b799f5604417c83c799c3ff513864502f5ef67;hpb=c497f56e8a7f09c4c328bd7560631d8773b7e676

diff --git a/strategy.tex b/strategy.tex
index c870cfb..a4716b3 100644
--- a/strategy.tex
+++ b/strategy.tex
@@ -104,8 +104,23 @@ during the update algorithm).
 
 \item[ $\tipcn, \tipcy$ ]
 The new tips of the git branches $\pcn$ and $\pcy$, containing
-all the correct commits (and the correct other patches), as
-generated by the Traversal phase of the update algorithm.
+all the appropriate commits (and the appropriate other patches),
+as generated by the Traversal phase of the update algorithm.
 
-\end{basedescript}
+\item[ $\allreach$ ]
+The set of all reachable commits.
+
+A reachable commit is one we might refer to explicitly in any of these
+algorithms, and any ancestor of such a commit.  We explicitly
+enumerate all of the input commits ($\allsrcs$), so the reachable
+commits are originally the input commits and their ancestors.
+
+$\allreach$ varies over time as we generate more commits.  Each
+commit we generate will have only reachable commits as ancestors, so
+generating a new commit (only) adds that new commit to $\allreach$.
 
+\item[ $\allreachof{\py}$ ]
+The set of reachable commits at the point where we have just generated
+$\tippy$, i.e. just after $\alg{Merge-Tip}(\p)$.
+
+\end{basedescript}