diff --git a/info4/kapitel-1/FormaleSprachen.ipynb b/info4/kapitel-1/FormaleSprachen.ipynb
index e453c1af09938570ac3708cd933ff4df63449545..8739d6a7b53dbfacf29400ba8f7d103c67a5eaa1 100644
--- a/info4/kapitel-1/FormaleSprachen.ipynb
+++ b/info4/kapitel-1/FormaleSprachen.ipynb
@@ -962,7 +962,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 36,
+   "execution_count": 56,
    "metadata": {},
    "outputs": [
     {
@@ -971,7 +971,7 @@
        "Loaded machine: Alphabet"
       ]
      },
-     "execution_count": 36,
+     "execution_count": 56,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -979,26 +979,26 @@
    "source": [
     "::load\n",
     "MACHINE Alphabet\n",
-    "SETS Σ = {a,b,c}\n",
+    "SETS Sigma = {a,b,c}\n",
     "CONSTANTS ε, Sprachen, w₁, w₂, L₁, L₂\n",
     "ABSTRACT_CONSTANTS\n",
     " teilwort, präfix\n",
     "PROPERTIES \n",
-    "  ε ∈ seq(Σ) ∧ size(ε) = 0 ∧\n",
-    "  Sprachen = {L | L ⊆ seq(Σ)}∧\n",
+    "  ε ∈ seq(Sigma) ∧ size(ε) = 0 ∧\n",
+    "  Sprachen = {L | L ⊆ seq(Sigma)}∧\n",
     "  w₁ = [a,a,b,c] ∧\n",
     "  w₂ = [c,a,b,a] ∧\n",
     "  L₁ = {w₁,w₂} ∧\n",
     "  L₂ = {w₂, [a,a,a] } ∧\n",
-    "  teilwort = {ut,vt | ut∈seq(Σ) & vt∈seq(Σ) ∧ ∃(vt1,vt2).(vt1^ut^vt2 = vt)} ∧\n",
-    "  präfix = {up,vp | up∈seq(Σ) & vp∈seq(Σ) ∧ ∃(wp).(up^wp = vp)}\n",
+    "  teilwort = {ut,vt | ut∈seq(Sigma) & vt∈seq(Sigma) ∧ ∃(vt1,vt2).(vt1^ut^vt2 = vt)} ∧\n",
+    "  präfix = {up,vp | up∈seq(Sigma) & vp∈seq(Sigma) ∧ ∃(wp).(up^wp = vp)}\n",
     "DEFINITIONS SET_PREF_PP_SEQUENCES == TRUE\n",
     "END"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 37,
+   "execution_count": 57,
    "metadata": {},
    "outputs": [
     {
@@ -1007,7 +1007,7 @@
        "Machine constants set up using operation 0: $setup_constants()"
       ]
      },
-     "execution_count": 37,
+     "execution_count": 57,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1018,19 +1018,25 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 38,
+   "execution_count": 58,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/markdown": [
-       "$\\mathit{TRUE}$"
+       "$\\mathit{TRUE}$\n",
+       "\n",
+       "**Solution:**\n",
+       "* $\\mathit{TW} = \\{[],[a],[a,b],[b],[b,c],[c],[a,\\mathit{b},c]\\}$"
       ],
       "text/plain": [
-       "TRUE"
+       "TRUE\n",
+       "\n",
+       "Solution:\n",
+       "\tTW = {[],[a],[a,b],[b],[b,c],[c],[a,b,c]}"
       ]
      },
-     "execution_count": 38,
+     "execution_count": 58,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1041,7 +1047,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 39,
+   "execution_count": 59,
    "metadata": {},
    "outputs": [
     {
@@ -1053,7 +1059,7 @@
        "FALSE"
       ]
      },
-     "execution_count": 39,
+     "execution_count": 59,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1064,19 +1070,25 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 40,
+   "execution_count": 60,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/markdown": [
-       "$\\mathit{TRUE}$"
+       "$\\mathit{TRUE}$\n",
+       "\n",
+       "**Solution:**\n",
+       "* $\\mathit{TW} = \\{[],[a],[a,b],[b],[b,c],[c],[a,\\mathit{b},c]\\}$"
       ],
       "text/plain": [
-       "TRUE"
+       "TRUE\n",
+       "\n",
+       "Solution:\n",
+       "\tTW = {[],[a],[a,b],[b],[b,c],[c],[a,b,c]}"
       ]
      },
-     "execution_count": 40,
+     "execution_count": 60,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1094,7 +1106,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 41,
+   "execution_count": 61,
    "metadata": {},
    "outputs": [
     {
@@ -1106,7 +1118,7 @@
        "{[],[c],[c,b],[c,b,a],[c,b,a,a],[c,b,a,a,b]}"
       ]
      },
-     "execution_count": 41,
+     "execution_count": 61,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1117,7 +1129,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 42,
+   "execution_count": 62,
    "metadata": {},
    "outputs": [
     {
@@ -1129,7 +1141,7 @@
        "{[],[a],[a,a],[a,b],[b],[b,a],[c],[c,b],[a,a,b],[b,a,a],[b,a,a,b],[c,b,a],[c,b,a,a],[c,b,a,a,b]}"
       ]
      },
-     "execution_count": 42,
+     "execution_count": 62,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1140,7 +1152,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 51,
+   "execution_count": 63,
    "metadata": {},
    "outputs": [
     {
@@ -1152,7 +1164,7 @@
        "{[],[a],[a,b],[b],[b,c],[c],[a,b,c]}"
       ]
      },
-     "execution_count": 51,
+     "execution_count": 63,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1163,7 +1175,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 52,
+   "execution_count": 64,
    "metadata": {},
    "outputs": [
     {
@@ -1172,7 +1184,7 @@
        "Preference changed: DOT_DECOMPOSE_NODES = FALSE\n"
       ]
      },
-     "execution_count": 52,
+     "execution_count": 64,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1183,7 +1195,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 53,
+   "execution_count": 65,
    "metadata": {},
    "outputs": [
     {
@@ -1374,7 +1386,7 @@
        "<Dot visualization: expr_as_graph [TWTW={[],[a],[a,b],[b],[b,c],[c],[a,b,c]}(\"tw\",{x,y|(x,y):teilwort & y:TW})]>"
       ]
      },
-     "execution_count": 53,
+     "execution_count": 65,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1385,7 +1397,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 55,
+   "execution_count": 66,
    "metadata": {},
    "outputs": [
     {
@@ -1546,7 +1558,7 @@
        "<Dot visualization: expr_as_graph [TWTW={[],[a],[a,b],[b],[b,c],[c],[a,b,c]}(\"präfix\",{x,y|(x,y):präfix & y:TW})]>"
       ]
      },
-     "execution_count": 55,
+     "execution_count": 66,
      "metadata": {},
      "output_type": "execute_result"
     }