diff --git a/search.ipynb b/search.ipynb
index 0d9fa5e72..365a6c1f2 100644
--- a/search.ipynb
+++ b/search.ipynb
@@ -2853,6 +2853,7 @@
     "        neighbor = argmax_random_tie(neighbors,\n",
     "                                     key=lambda node: problem.value(node.state))\n",
     "        if problem.value(neighbor.state) <= problem.value(current.state):\n",
+    "        \"\"\"Note that it is based on negative path cost method\"\"\"\n",    
     "            current.state = neighbor.state\n",
     "        iterations -= 1\n",
     "        \n",