diff --git a/info4/kapitel-3/PDA_nach_kfG.ipynb b/info4/kapitel-3/PDA_nach_kfG.ipynb
index 398744a8c6e07c6ec8da022b410b460369ac200c..d6615951606f9375ce7b0abc7969733a4ecc1d08 100644
--- a/info4/kapitel-3/PDA_nach_kfG.ipynb
+++ b/info4/kapitel-3/PDA_nach_kfG.ipynb
@@ -46,8 +46,7 @@
     " \"LibraryStrings.def\";\n",
     " ANIMATION_FUNCTION1 == {r,c,i| r=1 ∧ c∈dom(cur) ∧\n",
     "         i= IF ∃t.(t∈SYMBOLE ∧ cur(c) = (symbol |->t|-> symbol))\n",
-    "            THEN LET s BE s=TO_STRING({x | (symbol|->x|->symbol)=cur(c)})\n",
-    "                IN SUB_STRING(s,2,STRING_LENGTH(s)-2) END\n",
+    "            THEN TO_STRING(prj2(Z,SYMBOLE)(prj1((Z*SYMBOLE),Z)(cur(c))))\n",
     "            ELSE TO_STRING(cur(c)) END};\n",
     " ANIMATION_STR_JUSTIFY_LEFT == TRUE;\n",
     " SET_PREF_PP_SEQUENCES == TRUE\n",