--- a/ProgTutorial/Intro.thy	Fri Oct 29 12:51:44 2010 +0200
+++ b/ProgTutorial/Intro.thy	Fri Oct 29 12:57:44 2010 +0200
@@ -156,7 +156,7 @@
   \isacommand{ML}~@{text "\<verbopen>\<dots>\<verbclose>"} section). So you can copy
   (self-contained) chunks of existing code into a separate theory file and then
   study it alongside with examples. You can also install ``probes'' inside the
-  copied code without having to recompile the whole Isabelle distributions. Such
+  copied code without having to recompile the whole Isabelle distribution. Such
   probes might be messages or printouts of variables (see chapter
   \ref{chp:firststeps}). Although PolyML also contains a debugger, it seems
   probing the code with explicit print statements is the most effective method