From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sat, 10 Aug 2013 14:53:50 +0000 (+0100)
Subject: pseudomerge: Fix Foreign Inclusion
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?a=commitdiff_plain;h=294a235fb0c1167d1101866cb35f41ddfabc287b;p=topbloke-formulae.git

pseudomerge: Fix Foreign Inclusion
---

diff --git a/pseudomerge.tex b/pseudomerge.tex
index 27b2e52..c1a88f8 100644
--- a/pseudomerge.tex
+++ b/pseudomerge.tex
@@ -88,7 +88,15 @@ Explicitly dealt with by our Unique Tips condition.
 
 \subsection{Foreign Inclusion}
 
-True by Foreign Identical, and Foreign Inclusion of $L$.
+We need to consider $D \in \foreign$.
+
+For $D = C$: $D \has C$, $D \le C$; OK.
+
+For $D \neq C$: $D \has C \equiv D \has L$ by construction.
+$D \has L \equiv D \le L$ by Foreign Inclusion of $L$.
+$D \neq C$ so this $D \le L \equiv D \le C$.
+
+$\qed$
 
 \subsection{Foreign Ancestry}