diff -r cb9d47632573 -r 2665170f104a doc-src/TutorialI/Misc/document/natsum.tex
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/doc-src/TutorialI/Misc/document/natsum.tex	Wed Apr 19 12:59:38 2000 +0200
@@ -0,0 +1,22 @@
+\begin{isabelle}%
+%
+\begin{isamarkuptext}%
+\noindent
+In particular, there are \isa{case}-expressions, for example%
+\end{isamarkuptext}%
+~{"}case~n~of~0~{\isasymRightarrow}~0~|~Suc~m~{\isasymRightarrow}~m{"}%
+\begin{isamarkuptext}%
+\noindent
+primitive recursion, for example%
+\end{isamarkuptext}%
+\isacommand{consts}~sum~::~{"}nat~{\isasymRightarrow}~nat{"}\isanewline
+\isacommand{primrec}~{"}sum~0~=~0{"}\isanewline
+~~~~~~~~{"}sum~(Suc~n)~=~Suc~n~+~sum~n{"}%
+\begin{isamarkuptext}%
+\noindent
+and induction, for example%
+\end{isamarkuptext}%
+\isacommand{lemma}~{"}sum~n~+~sum~n~=~n*(Suc~n){"}\isanewline
+\isacommand{apply}(induct\_tac~n)\isanewline
+\isacommand{apply}(auto)\isacommand{.}\isanewline
+\end{isabelle}%