invariants: introduce bases' children; some of the proofs

[topbloke-formulae.git] / invariants.tex

diff --git a/invariants.tex b/invariants.tex
index bb926ea1f71460e1db981d110bf06078ab818a78..3134e5c9cde1d48718b1cfb70d883a9e624c0283 100644 (file)
--- a/invariants.tex
+++ b/invariants.tex
@@ -28,6 +28,11 @@ We maintain these each time we construct a new commit. \\
   \bigforall_{C \in \foreign}
     D \le C \implies \isforeign{D}
 }\]
+\[\eqn{Bases' Children}{
+  C \hasparent D \land D \in \pn
+    \implies
+  C \in \pn \lor C \in \py
+}\]
 
 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