Problem $ P$

The engineering process starts with some problem description $ P$. Here a simple example:

PROBLEM P: The entrance of some building shall be secured by an electronic key which shall be activated by entering a sequence of keys. In this example we assume as required sequence 'A,C,A' from a three-letter alphabet available as a keypad with three buttons enscripted 'A', 'B', and 'C'. Only if such a sequence 'A,C,A' has been entered completely and without interruptions then the door shall change from 'being closed' to 'being open'. Only then a person can enter the door.

This induces a use case where a human person as an actor $ U$ tries to solve the task $ T$ Open the door by entering a correct sequence of letters.



Gerd Doeben-Henisch 2010-03-03