1.1 --- a/doc-src/TutorialI/Trie/Trie.thy	Wed Jan 24 11:59:15 2001 +0100
     1.2 +++ b/doc-src/TutorialI/Trie/Trie.thy	Wed Jan 24 12:29:10 2001 +0100
     1.3 @@ -130,7 +130,7 @@
     1.4  This proof may look surprisingly straightforward. However, note that this
     1.5  comes at a cost: the proof script is unreadable because the intermediate
     1.6  proof states are invisible, and we rely on the (possibly brittle) magic of
     1.7 -@{text auto} (@{text simp_all} will not do---try it) to split the subgoals
     1.8 +@{text auto} (@{text simp_all} will not do --- try it) to split the subgoals
     1.9  of the induction up in such a way that case distinction on @{term bs} makes
    1.10  sense and solves the proof. Part~\ref{Isar} shows you how to write readable
    1.11  and stable proofs.