+By Insertion Acyclic, $D \not\isin R^+$. xxx this is wrong
+By Tip Contents for $R^+$,
+$D \isin R^+ \equiv D \isin R^- \lor (D \in \pry \land ...)$
+but $D \in \py$ so $D \not\in \pry$. So $D \not\isin R^-$.
+By $\merge$, $D \isin C \equiv D \isin L$.
+
+If $L \nothaspatch \p$, $D \not\isin L$ so $C \nothaspatch \p$. OK.
+
+If $L \haspatch \p$, Others' Ends applies; by Transitive
+Ancestors, $A \in \pancsof{R^+}{\py} \implies A \le L$.
+So $D \le R^+$, which is the same as $D \in \pancsof{R^+}{\py}$,
+$\implies D \le L$. Thus $D le C \equiv D \le L$.
+And by $\haspatch$, $D \le L \equiv D \isin L$ so
+$D \isin C \equiv D \le C$. Thus $C \haspatch \p$.
+OK.
+
+$\qed$