X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=topbloke-formulae.git;a=blobdiff_plain;f=invariants.tex;h=bc3813e6b83593e5d5ad0ad9c2b59c9a0f53d000;hp=ab0349110d651d3e1109c5723bdd874f103c1de3;hb=79a138e6a8c3902ba6f9708fc7c57c8d834f5dc6;hpb=3b81991eea75c33566f4948506277ef61b058d1c

diff --git a/invariants.tex b/invariants.tex
index ab03491..bc3813e 100644
--- a/invariants.tex
+++ b/invariants.tex
@@ -18,6 +18,9 @@ We maintain these each time we construct a new commit. \\
 \[\eqn{Coherence:}{
   \bigforall_{C,\p} C \haspatch \p \lor C \nothaspatch \p
 }\]
+\[\eqn{Unique Tips:}{
+  \bigforall_{C,\p} C \haspatch \p \implies \pendsof{C}{\p} = \{ T \}
+}\]
 \[\eqn{Foreign Inclusion:}{
   \bigforall_{D \text{ s.t. } \patchof{D} = \bot} D \isin C \equiv D \leq C
 }\]
@@ -26,6 +29,10 @@ We maintain these each time we construct a new commit. \\
     D \le C \implies \patchof{D} = \bot
 }\]
 
+We also assign each new commit $C$ to zero or one of the sets $\p$, as
+stated in the definition of $\patchof{C}$ in the summary for each kind
+of commit.
+
 A commit $C$ which satisfies all of the above is said to be
 ``conformant''.