--- a/doc-src/TutorialI/Recdef/simplification.thy Fri Sep 01 18:29:52 2000 +0200
+++ b/doc-src/TutorialI/Recdef/simplification.thy Fri Sep 01 19:09:44 2000 +0200
@@ -7,7 +7,7 @@
equations become simplification rules, just as with
\isacommand{primrec}. In most cases this works fine, but there is a subtle
problem that must be mentioned: simplification may not
-terminate because of automatic splitting of @{name"if"}.
+terminate because of automatic splitting of @{text"if"}.
Let us look at an example:
*}
@@ -24,9 +24,9 @@
is provded automatically because it is already present as a lemma in the
arithmetic library. Thus the recursion equation becomes a simplification
rule. Of course the equation is nonterminating if we are allowed to unfold
-the recursive call inside the @{name"if"} branch, which is why programming
+the recursive call inside the @{text"if"} branch, which is why programming
languages and our simplifier don't do that. Unfortunately the simplifier does
-something else which leads to the same problem: it splits @{name"if"}s if the
+something else which leads to the same problem: it splits @{text"if"}s if the
condition simplifies to neither @{term"True"} nor @{term"False"}. For
example, simplification reduces
\begin{quote}
@@ -41,17 +41,18 @@
@{term[display]"(n=0 --> m=k) & (n ~= 0 --> gcd(n, m mod n)=k)"}
\end{quote}
Since the recursive call @{term"gcd(n, m mod n)"} is no longer protected by
-an @{name"if"}, it is unfolded again, which leads to an infinite chain of
+an @{text"if"}, it is unfolded again, which leads to an infinite chain of
simplification steps. Fortunately, this problem can be avoided in many
different ways.
-The most radical solution is to disable the offending \@{name"split_if"} as
-shown in the section on case splits in \S\ref{sec:Simplification}. However,
-we do not recommend this because it means you will often have to invoke the
-rule explicitly when @{name"if"} is involved.
+The most radical solution is to disable the offending
+@{thm[source]split_if} as shown in the section on case splits in
+\S\ref{sec:Simplification}. However, we do not recommend this because it
+means you will often have to invoke the rule explicitly when @{text"if"} is
+involved.
If possible, the definition should be given by pattern matching on the left
-rather than @{name"if"} on the right. In the case of @{term"gcd"} the
+rather than @{text"if"} on the right. In the case of @{term"gcd"} the
following alternative definition suggests itself:
*}
@@ -66,7 +67,7 @@
@{prop"n ~= 0"}. Unfortunately, in general the case distinction
may not be expressible by pattern matching.
-A very simple alternative is to replace @{name"if"} by @{name"case"}, which
+A very simple alternative is to replace @{text"if"} by @{text"case"}, which
is also available for @{typ"bool"} but is not split automatically:
*}