From 7529edb3027da350671d9295129ee655d0112d55 Mon Sep 17 00:00:00 2001
From: Philip Kaludercic <philip.kaludercic@fau.de>
Date: Fri, 22 Mar 2024 15:03:40 +0100
Subject: [PATCH] Add Worwell's theorem

---
 coalgebra.tex | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/coalgebra.tex b/coalgebra.tex
index c8c9602..0df45f0 100644
--- a/coalgebra.tex
+++ b/coalgebra.tex
@@ -41,6 +41,13 @@
   \[ \nu F = \colim_{n < \omega} F^n \terminal. \]
 \end{definition}
 
+\begin{theorem}[Worwell]
+  For a \de{finitary} \de{functor} \(F\),
+  \(\nu F = F^{\omega+\omega}1\), that is to say one extends and
+  repeats the \(\op{\omega}\)-chain, starting with
+  \(\nu F = F^\omega\) instead of \(\terminal\).
+\end{theorem}
+
 \begin{definition}\label{def:beheqiv}
   For a \de{endofunctor} \(F : \map{\Set}{\Set}\) and two \fca{}
   \((C, c)\), \((D, d)\), are \emph{behaviourally equivalent} for
-- 
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