From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 25 Mar 2012 20:02:02 +0000 (+0100)
Subject: clarify merge complex D=C
X-Git-Tag: f0.3~8
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=topbloke-formulae.git;a=commitdiff_plain;h=cb5a9d3227f121506751f47f098e53ced767a278

clarify merge complex D=C
---

diff --git a/merge.tex b/merge.tex
index 90f5ab2..48e7270 100644
--- a/merge.tex
+++ b/merge.tex
@@ -172,7 +172,8 @@ $F \le C$ so this suffices.
 Consider $D = C$:  Thus $C \in \py, L \in \py$.
 By Tip Own Contents, $L \haspatch \p$ so $L \neq X$,
 therefore we must have $L=Y$, $R=X$.
-By Tip Merge $M = \baseof{L}$ so $M \in \pn$ so
+Conversely $R \not\in \py$
+so by Tip Merge $M = \baseof{L}$.  Thus $M \in \pn$ so
 by Base Acyclic $M \nothaspatch \p$.  By $\merge$, $D \isin C$,
 and $D \le C$.  OK.