add schedule flight crews

Author: khuyentran1401

mathematical_programming/schedule_flight_crew/flight_crew_schedule.ipynb

@@ -572,7 +572,7 @@
    "source": [
     "Decision variable: \n",
     "\n",
-    "$y_j=1$ or $0$: Whether a crew is assigned to the sequence of flight $j$"
+    "$y_j=1$ or $0$: Whether the flight sequence $j$ is selected"
    ]
   },
   {
@@ -1028,7 +1028,7 @@
    "metadata": {},
    "source": [
     "Constraints:\n",
-    "* There must be at least one crew per flight\n",
+    "* There must be at least one airplane per flight\n",
     "$$a \\cdot y\\geq b$$\n",
     "\n",
     "* The total hours of flights must be less than or equal to 1700\n",