Docs: fix reference to America/Rutten.

docs/program-logic.tex

@@ -36,10 +36,8 @@ Furthermore, since the $\iFunc_i$ are locally contractive, so is $\textdom{ResF}
 
 Now we can write down the recursive domain equation:
 \[ \iPreProp \cong \UPred(\textdom{ResF}(\iPreProp, \iPreProp)) \]
-$\iPreProp$ is a COFE defined as the fixed-point of a locally contractive bifunctor.
-This fixed-point exists and is unique\footnote{We have not proven uniqueness in Coq.} by America and Rutten's theorem~\cite{America-Rutten:JCSS89,birkedal:metric-space}.
-We do not need to consider how the object is constructed. 
-We only need the isomorphism, given by
+Here, $\iPreProp$ is a COFE defined as the fixed-point of a locally contractive bifunctor, which exists by \thmref{thm:america_rutten}.
+We do not need to consider how the object $\iPreProp$ is constructed, we only need the isomorphism, given by:
 \begin{align*}
   \Res &\eqdef \textdom{ResF}(\iPreProp, \iPreProp) \\
   \iProp &\eqdef \UPred(\Res) \\