fixed comment;

--- a/src/HOL/Induct/Acc.thy	Thu Oct 14 15:04:36 1999 +0200
+++ b/src/HOL/Induct/Acc.thy	Thu Oct 14 15:05:35 1999 +0200
@@ -9,7 +9,7 @@
 Research Report 92-49, LIP, ENS Lyon.  Dec 1992.
 *)
 
-header {* The acessible part of a relation *};
+header {* The accessible part of a relation *};
 
 theory Acc = WF + Inductive:;