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ipynb/Cheryl.ipynb

@@ -261,7 +261,7 @@
    "source": [
     "The function `statement3` takes as input a single possible birthdate and returns `True` if Albert's statement is true for that birthdate. How do we go from Albert's English statement to a Python function? Let's paraphrase it in a form that uses the concepts we have defined:\n",
     "\n",
-    "> **Albert**: After Cheryl **told** me the **month** of her birthdate, my **belief set** was such that I didn't **know** her birthday.  I do know that Bernard does not know. How do I know that? I can see that for **all** the possible dates in my **belief set**, if Bernard was **told** the **day** of that date, he would **not know** Cheryl's birthday.\n",
+    "> **Albert**: After Cheryl **told** me the **month** of her birthdate, my **belief set** was such that I didn't **know** her birthday.  And I know that Bernard does not know; in other words he could not make the statement that he knows. How do I know that? I can see that for all the possible dates in my **belief set**, if Bernard was **told** the **day** of that date, he would **not know** Cheryl's birthday.\n",
     "\n",
     "That I can translate directly into code:"
    ]
@@ -275,9 +275,9 @@
     "def statement3(date) -> bool:\n",
     "    \"\"\"Albert: I don't know when Cheryl's birthday is, but I know that Bernard does not know too.\"\"\"\n",
     "    albert_beliefs = told(month(date))\n",
-    "    return (not know(albert_beliefs) \n",
+    "    return not know(albert_beliefs) and not satisfy(albert_beliefs, bernard_knows)\n",
-    "            and all(not know(told(day(d))) \n",
+    "\n",
-    "                    for d in albert_beliefs))"
+    "def bernard_knows(date) -> bool: return know(told(day(date))) "
    ]
   },
   {
@@ -481,7 +481,8 @@
     }
    ],
    "source": [
-    "dates = '06:32, 06:43, 06:50, 07:17, 07:46, 08:19, 08:32, 09:17, 09:19, 09:50'.replace(':', ' ').split(', ')\n",
+    "times = '06:32 06:43 06:50 07:17 07:46 08:19 08:32 09:17 09:19 09:50'.split()\n",
+    "dates = [t.replace(':', ' ') for t in times]\n",
     "\n",
     "cheryls_birthday()"
    ]