+\subsection{Single Parent Unique Tips}
+
+Unique Tips is satisfied for single-parent commits. Formally,
+given a conformant commit $A$,
+$$
+ \Big[
+ C \hasparents \{ A \}
+ \Big] \implies \left[
+ \bigforall_{P \patchisin C} \pendsof{C}{\py} = \{ T \}
+ \right]
+$$
+\proof{
+ Trivial for $C \in \py$.
+ For $C \not\in \py$, $\pancsof{C}{\py} = \pancsof{A}{\py}$,
+ so Unique Tips of $A$ suffices.
+}
+