diff -r a474900d5bd2 -r 255c853ea2f0 src/Tools/isac/Knowledge/Simplify.thy
--- a/src/Tools/isac/Knowledge/Simplify.thy	Thu Dec 22 11:12:18 2016 +0100
+++ b/src/Tools/isac/Knowledge/Simplify.thy	Thu Dec 22 11:36:20 2016 +0100
@@ -56,7 +56,7 @@
 (** CAS-command **)
 
 (*.function for handling the cas-input "Simplify (2*a + 3*a)":
-   make a model which is already in ptree-internal format.*)
+   make a model which is already in ctree-internal format.*)
 (* val (h,argl) = strip_comb (str2term "Simplify (2*a + 3*a)");
    val (h,argl) = strip_comb ((Thm.term_of o the o (parse (Thy_Info.get_theory "Simplify"))) 
 				  "Simplify (2*a + 3*a)");