+ * As UDPOR performs its search, it moves the application-side along with
+ * it so that the application is always providing the checker with
+ * the correct information about what each actor is running (and whether
+ * those actors are enabled) at the state reached by the configuration it
+ * decides to search.
+ *
+ * When UDPOR decides to "backtrack" (e.g. after reaching a configuration
+ * whose en(C) is empty), before it attempts to continue the search by taking
+ * a different path from a configuration it visited in the past, it must ensure
+ * that the application-side has moved back into `state(C)`.
+ *
+ * The search may have moved the application arbitrarily deep into its execution,
+ * and the search may backtrack arbitrarily closer to the beginning of the execution.
+ * The UDPOR implementation in SimGrid ensures that the stack is updated appropriately,
+ * but the process must still be regenerated.