From ee2de71dcb9b272a248d3dd6b56a3ac7c00801e6 Mon Sep 17 00:00:00 2001
From: "David A. Madore" <david+git@madore.org>
Date: Fri, 7 May 2021 11:40:44 +0200
Subject: Missing rules in a grammar.

Thanks to some student in the course, via Matthieu Rambaud.
---
 errata-notes-inf105.tex | 21 +++++++++++++++++++++
 notes-inf105.tex        |  4 ++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/errata-notes-inf105.tex b/errata-notes-inf105.tex
index f233a55..acf5fe5 100644
--- a/errata-notes-inf105.tex
+++ b/errata-notes-inf105.tex
@@ -169,6 +169,27 @@ autres.
 
 \par}
 
+\hbox to\hsize{\hfill\hbox to4cm{\hrulefill}\hfill}
+
+\medskip
+
+Paragraphe 4.3.5, il manque à la grammaire $G'$ des productions $U
+\rightarrow \varepsilon$ et $V \rightarrow \varepsilon$ : page 58,
+lignes 4–5, remplacer
+\[
+\begin{aligned}
+U &\rightarrow aUbU\\
+V &\rightarrow bVaV\\
+\end{aligned}
+\]
+par
+\[
+\begin{aligned}
+U &\rightarrow aUbU \;|\; \varepsilon\\
+V &\rightarrow bVaV \;|\; \varepsilon\\
+\end{aligned}
+\]
+
 
 
 %
diff --git a/notes-inf105.tex b/notes-inf105.tex
index 67a0a9b..2bf2697 100644
--- a/notes-inf105.tex
+++ b/notes-inf105.tex
@@ -5162,8 +5162,8 @@ Un raisonnement analogue montre que la grammaire $G'$ donnée par
 \[
 \begin{aligned}
 S &\rightarrow aUbS \;|\; bVaS \;|\; \varepsilon\\
-U &\rightarrow aUbU\\
-V &\rightarrow bVaV\\
+U &\rightarrow aUbU \;|\; \varepsilon\\
+V &\rightarrow bVaV \;|\; \varepsilon\\
 \end{aligned}
 \]
 engendre le même langage $L = \{w \in\Sigma^* : |w|_a = |w|_b\}$ que
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