author paulson Thu, 08 May 2003 12:51:55 +0200 changeset 13978 a241cdd9c1c9 parent 13977 eb5fe146a4e0 child 13979 4c3a638828b9
auto update
--- a/doc-src/TutorialI/ToyList/document/ToyList.tex	Thu May 08 12:50:27 2003 +0200
+++ b/doc-src/TutorialI/ToyList/document/ToyList.tex	Thu May 08 12:51:55 2003 +0200
@@ -153,25 +153,22 @@
Isabelle's response is to print the initial proof state consisting
of some header information (like how many subgoals there are) followed by
\begin{isabelle}%
-rev\ {\isacharparenleft}rev\ xs{\isacharparenright}\ {\isacharequal}\ xs\isanewline
\ {\isadigit{1}}{\isachardot}\ rev\ {\isacharparenleft}rev\ xs{\isacharparenright}\ {\isacharequal}\ xs%
\end{isabelle}
For compactness reasons we omit the header in this tutorial.
Until we have finished a proof, the \rmindex{proof state} proper
always looks like this:
\begin{isabelle}
-$G$\isanewline
~1.~$G\sb{1}$\isanewline
~~\vdots~~\isanewline
~$n$.~$G\sb{n}$
\end{isabelle}
-where $G$
-is the overall goal that we are trying to prove, and the numbered lines
-contain the subgoals $G\sb{1}$, \dots, $G\sb{n}$ that we need to prove to
-establish $G$.\index{subgoals}
-Initially there is only one subgoal, which is
-identical with the overall goal.  Normally $G$ is constant and only serves as
-a reminder. Hence we rarely show it in this tutorial.
+The numbered lines contain the subgoals $G\sb{1}$, \dots, $G\sb{n}$
+that we need to prove to establish the main goal.\index{subgoals}
+Initially there is only one subgoal, which is identical with the
+main goal. (If you always want to see the main goal as well,
+set the flag \isa{Proof.show_main_goal}\index{*show_main_goal (flag)}
+--- this flag used to be set by default.)

Let us now get back to \isa{rev\ {\isacharparenleft}rev\ xs{\isacharparenright}\ {\isacharequal}\ xs}. Properties of recursively
defined functions are best established by induction. In this case there is