X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=topbloke-formulae.git;a=blobdiff_plain;f=strategy.tex;h=e2017c34c3fcd516d308438ab5c6f33f3b577583;hp=bfd392224d6e5c854573b4988f4314fd66d40530;hb=1768ad396360b5f7145450858b4bae1e9d1c7b05;hpb=9487356344b09d6e8276c9a93a7a58913afcf259

diff --git a/strategy.tex b/strategy.tex
index bfd3922..e2017c3 100644
--- a/strategy.tex
+++ b/strategy.tex
@@ -54,6 +54,13 @@ $\bigforall_{E \in \pendsof{\set X}{\p}} E \le T$
 $\bigcup_{\p \in \allpatches} \set H^{\pn} \cup \set H^{\py}$.
 All the input commits to the update algorithm.  (See below.)
 
+\item[ $\set H^{\pc^{_=/-}}$ ]
+
+The existing head commit(s) $\set H$ of the branch $\pc^{+/-}$.
+These are the heads which will be merged and used in this update.
+This will include the current local and remote git refs, as desired.
+Obtained from the function $h$ (see below).
+
 %\item[ $\set E_{\pc}$ ]
 %$ \bigcup_i \pendsof{S_{\pc,i}}{\pc} $.
 %All the ends of $\pc$ in the sources.
@@ -76,8 +83,6 @@ all of its dependencies will be updated.
 
 \item[ $h : \pc^{+/-} \mapsto \set H^{\pc^{+/-}}$ ]
 Function for getting the existing heads $\set H$ of the branch $\pc^{+/-}$.
-These are the heads which will be merged and used in this update.
-This will include the current local and remote git refs, as desired.
 
 \item[ $g : \pc, \Gamma \mapsto \Gamma'$ ]
 Function to allow explicit adjustment of the direct dependencies
@@ -107,5 +112,20 @@ The new tips of the git branches $\pcn$ and $\pcy$, containing
 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}