+Then we will merge the direct contributors and the sources' ends.
+
+This generates more commits $\tipuc \in \pc$, but none in any other
+commit set. We maintain XXX FIXME IS THIS THE BEST THING?
+$$
+ \bigforall_{\p \isdep \pc}
+ \pancsof{\tipcc}{\p} \subset \left[
+ \tipfa \p \cup
+ \bigcup_{E \in \set E_{\pc}} \pancsof{E}{\p}
+ \right]
+$$
+