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[topbloke-formulae.git] / create-tip.tex

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+\section{Create Tip}
+
+Given a Topbloke base $B$ for a patch $\pq$,
+create a tip branch initial commit B.
+\gathbegin
+ C \hasparents \{ B \}
+\gathnext
+ \patchof{B} = \pqy
+\gathnext
+ D \isin C \equiv D \isin B \lor D = C
+\end{gather}
+
+\subsection{Conditions}
+
+\[ \eqn{ Ingredients }{
+ \patchof{B} = \pqn
+}\]
+\[ \eqn{ No Sneak }{
+ \pendsof{B}{\pqy} = \{ \}
+}\]
+
+\subsection{No Replay}
+
+Ingredients Prevent Replay applies.  $\qed$
+
+\subsection{Unique Base}
+
+Trivially, $\pendsof{C}{\pqn} = \{B\}$ so $\baseof{C} = B$.  $\qed$
+
+\subsection{Tip Contents}
+
+Consider some arbitrary commit $D$.  If $D = C$, trivially satisfied.
+
+If $D \neq C$, $D \isin C \equiv D \isin B$,
+which by Unique Base, above, $ \equiv D \isin \baseof{B}$.
+By Base Acyclic of $B$, $D \isin B \implies D \not\in \pqy$.
+
+
+$\qed$
+
+\subsection{Base Acyclic}
+
+Not applicable.
+
+\subsection{Coherence and Patch Inclusion}
+
+$$
+\begin{cases}
+  \p = \pq    \lor B \haspatch \p : & C \haspatch \p \\
+  \p \neq \pq \land B \nothaspatch \p : & C \nothaspatch \p
+\end{cases}
+$$
+
+\proofstarts
+~ Consider some $D \in \py$.
+
+\subsubsection{For $\p = \pq$:}
+
+By Base Acyclic, $D \not\isin B$.  So $D \isin C \equiv D = C$.
+By No Sneak, $D \not\le B$ so $D \le C \equiv D = C$.  Thus $C \haspatch \pq$.
+
+\subsubsection{For $\p \neq \pq$:}
+
+$D \neq C$.  So $D \isin C \equiv D \isin B$,
+and $D \le C \equiv D \le B$.
+
+$\qed$
+
+\subsection{Foreign Inclusion}
+
+Simple Foreign Inclusion applies.  $\qed$
+
+\subsection{Foreign Contents}
+
+Not applicable.
+