diff --git a/aircraft-loading-optim.ipynb b/aircraft-loading-optim.ipynb
index ebffd3b..b0d369d 100644
--- a/aircraft-loading-optim.ipynb
+++ b/aircraft-loading-optim.ipynb
@@ -51,7 +51,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 3,
+   "execution_count": 4,
    "id": "7cdda786-f949-4921-b997-3edc27b1f7e9",
    "metadata": {},
    "outputs": [],
@@ -74,6 +74,9 @@
     " \n",
     "K = n + N + (len(bin(W))-2) # number of slack variables: K = n + N + number of bits of binary expansion of W\n",
     "\n",
+    "# len(z) equals the number of qubits in QAOA circuit\n",
+    "z=[sym.Symbol(f'z_{i}') for i in range(n*N+K)]\n",
+    "\n",
     "# Load results obtained from Mathematica notebook airbus.nb\n",
     "def read_quadratic(path):\n",
     "    lines=[]\n",
@@ -118,7 +121,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 4,
+   "execution_count": 5,
    "id": "52cc9f3d-ced0-49fc-becd-0024cb85863a",
    "metadata": {},
    "outputs": [],
@@ -146,7 +149,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 5,
+   "execution_count": 6,
    "id": "27bd9fb8-3f68-4f40-b9cb-fe373d92d61b",
    "metadata": {},
    "outputs": [
@@ -173,7 +176,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 6,
+   "execution_count": 7,
    "id": "d981f899-0de3-48c0-b556-3b7ff8d0917e",
    "metadata": {},
    "outputs": [],
@@ -183,7 +186,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 13,
+   "execution_count": 8,
    "id": "a1e9dec1-e652-4999-8ebc-2289624681d9",
    "metadata": {},
    "outputs": [
@@ -195,18 +198,9 @@
       "[DYNEX] PRECISION SET TO 1\n",
       "[DYNEX] SAMPLER INITIALISED\n",
       "[DYNEX|TESTNET] *** WAITING FOR READS ***\n",
-      "╭────────────┬─────────────┬───────────┬───────────────────────────┬─────────┬─────────┬────────────────╮\n",
-      "│   DYNEXJOB │   BLOCK FEE │ ELAPSED   │ WORKERS READ              │ CHIPS   │ STEPS   │ GROUND STATE   │\n",
-      "├────────────┼─────────────┼───────────┼───────────────────────────┼─────────┼─────────┼────────────────┤\n",
-      "│         -1 │           0 │           │ *** WAITING FOR READS *** │         │         │                │\n",
-      "╰────────────┴─────────────┴───────────┴───────────────────────────┴─────────┴─────────┴────────────────╯\n",
-      "\n",
-      "[DYNEX] FINISHED READ AFTER 0.00 SECONDS\n",
-      "[DYNEX] SAMPLESET READY\n",
+      "[DYNEX] Keyboard interrupt\n",
       "Result:\n",
-      "   0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 ... 770         energy num_oc.\n",
-      "0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0 ...   0 -1600039155.75       1\n",
-      "['BINARY', 1 rows, 1 samples, 771 variables]\n"
+      "{'error': 'Keyboard interrupt'}\n"
      ]
     }
    ],