diff --git a/sec4.2.ipynb b/sec4.2.ipynb
index 18b1fb2..f449a5e 100644
--- a/sec4.2.ipynb
+++ b/sec4.2.ipynb
@@ -2,218 +2,65 @@
  "cells": [
   {
    "cell_type": "code",
-   "execution_count": 1,
+   "execution_count": null,
    "id": "011c5f34-be40-4f0b-8146-73f66ba18672",
-   "metadata": {},
+   "metadata": {
+    "tags": []
+   },
    "outputs": [],
    "source": [
     "from algorithm.optimization.common import *\n",
-    "from algorithm.optimization.gradient import *"
+    "from algorithm.optimization.gradient import *\n",
+    "from IPython.display import IFrame"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 3,
-   "id": "a4827f0c",
-   "metadata": {},
-   "outputs": [
-    {
-     "data": {
-      "application/vnd.jupyter.widget-view+json": {
-       "model_id": "3879a8b297fa4dffacb2dc6aba04dc5f",
-       "version_major": 2,
-       "version_minor": 0
-      },
-      "text/plain": [
-       "VBox(children=(HBox(children=(VBox(children=(Text(value='sin(x) + sin((10.0 / 3.0) * x)', description='Express…"
-      ]
-     },
-     "metadata": {},
-     "output_type": "display_data"
-    },
-    {
-     "data": {
-      "application/vnd.jupyter.widget-view+json": {
-       "model_id": "8c7609027a8d4f56a8492fda092401b6",
-       "version_major": 2,
-       "version_minor": 0
-      },
-      "text/plain": [
-       "Output()"
-      ]
-     },
-     "metadata": {},
-     "output_type": "display_data"
-    },
-    {
-     "data": {
-      "application/vnd.jupyter.widget-view+json": {
-       "model_id": "1fa7e58deae44726bb5868c3454b3c4a",
-       "version_major": 2,
-       "version_minor": 0
-      },
-      "text/plain": [
-       "Output()"
-      ]
-     },
-     "metadata": {},
-     "output_type": "display_data"
-    },
-    {
-     "data": {
-      "text/plain": [
-       "<algorithm.optimization.gradient.gd_1d at 0x24697aae548>"
-      ]
-     },
-     "execution_count": 3,
-     "metadata": {},
-     "output_type": "execute_result"
-    }
-   ],
+   "execution_count": null,
+   "id": "7a1ba495-73ac-4710-bab7-edb429ab9628",
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [],
    "source": [
-    "gd_1d(environ=\"jupyterlab\")"
+    "IFrame(\"https://ufal.mff.cuni.cz/~straka/courses/npfl129/2223/demos/mnist_web.html\", width=1080, height=800)"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 5,
+   "execution_count": null,
+   "id": "a4827f0c",
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [],
+   "source": [
+    "gd1d(environ=\"jupyterlab\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
    "id": "f28bd167",
    "metadata": {
     "slideshow": {
      "slide_type": "subslide"
-    }
+    },
+    "tags": []
    },
-   "outputs": [
-    {
-     "data": {
-      "application/vnd.jupyter.widget-view+json": {
-       "model_id": "3e3eda22a6eb43bc836431a749170cc1",
-       "version_major": 2,
-       "version_minor": 0
-      },
-      "text/plain": [
-       "VBox(children=(HBox(children=(Dropdown(options=(('(1 - 8 * x1 + 7 * x1**2 - (7/3) * x1**3 + (1/4) * x1**4) * x…"
-      ]
-     },
-     "metadata": {},
-     "output_type": "display_data"
-    },
-    {
-     "data": {
-      "application/vnd.jupyter.widget-view+json": {
-       "model_id": "94b62fa1c4c24a359419e7b9087c63a4",
-       "version_major": 2,
-       "version_minor": 0
-      },
-      "text/plain": [
-       "Output()"
-      ]
-     },
-     "metadata": {},
-     "output_type": "display_data"
-    },
-    {
-     "data": {
-      "application/vnd.jupyter.widget-view+json": {
-       "model_id": "4eccbd5a5fd94a7ab11f561e2ba2d247",
-       "version_major": 2,
-       "version_minor": 0
-      },
-      "text/plain": [
-       "Output()"
-      ]
-     },
-     "metadata": {},
-     "output_type": "display_data"
-    },
-    {
-     "data": {
-      "application/vnd.jupyter.widget-view+json": {
-       "model_id": "2c3d255d1b984fc38f8f3da9ebb4fd38",
-       "version_major": 2,
-       "version_minor": 0
-      },
-      "text/plain": [
-       "Output()"
-      ]
-     },
-     "metadata": {},
-     "output_type": "display_data"
-    },
-    {
-     "data": {
-      "text/plain": [
-       "<algorithm.optimization.gradient.gd2d at 0x24697af6248>"
-      ]
-     },
-     "execution_count": 5,
-     "metadata": {},
-     "output_type": "execute_result"
-    }
-   ],
+   "outputs": [],
    "source": [
     "gd2d(environ=\"jupyterlab\")"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 6,
+   "execution_count": null,
    "id": "d5651fc9-3fcd-4e91-8d3c-04897da1ea02",
-   "metadata": {},
-   "outputs": [
-    {
-     "data": {
-      "application/vnd.jupyter.widget-view+json": {
-       "model_id": "6bf4e3de13db419883591537fc222a36",
-       "version_major": 2,
-       "version_minor": 0
-      },
-      "text/plain": [
-       "VBox(children=(HBox(children=(Dropdown(options=(('(1 - 8 * x1 + 7 * x1**2 - (7/3) * x1**3 + (1/4) * x1**4) * x…"
-      ]
-     },
-     "metadata": {},
-     "output_type": "display_data"
-    },
-    {
-     "data": {
-      "application/vnd.jupyter.widget-view+json": {
-       "model_id": "7aea5da550ff487da02c07710a3a5078",
-       "version_major": 2,
-       "version_minor": 0
-      },
-      "text/plain": [
-       "Output()"
-      ]
-     },
-     "metadata": {},
-     "output_type": "display_data"
-    },
-    {
-     "data": {
-      "application/vnd.jupyter.widget-view+json": {
-       "model_id": "7b8c6c9cbceb4eeaa1e1187cb01476af",
-       "version_major": 2,
-       "version_minor": 0
-      },
-      "text/plain": [
-       "Output()"
-      ]
-     },
-     "metadata": {},
-     "output_type": "display_data"
-    },
-    {
-     "data": {
-      "text/plain": [
-       "<algorithm.optimization.gradient.gd2d_compete at 0x24697e44788>"
-      ]
-     },
-     "execution_count": 6,
-     "metadata": {},
-     "output_type": "execute_result"
-    }
-   ],
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [],
    "source": [
     "gd2d_compete(environ=\"jupyterlab\")"
    ]
@@ -244,7 +91,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.13"
+   "version": "3.10.9"
   }
  },
  "nbformat": 4,