Systems Analysis and Synthesis

7.11. Exercises

1. Consider the Withdraw event, which undoes the work of Enrol, provided that the subject has not yet been frozen:

Withdraw(c,s)⇐e=(Current Semester,c,s);Enrolment State(e)=Enrolled;Subject State(s)=Offered;Enrolment State(e)′=Null;Filled(s)′=Filled(s)−1;Balance Owing(c)′=Balance Owing(c)−Fee(s).

     Construct a dependency matrix for the Withdraw event in the style of Table 7.1, marking the cells with the relevant rule or rules. (Use the same abbreviations as Table 7.1.)

2. Draw the state dependency graph for the Withdraw event in the style of Figure 7.3.

    Is the graph you obtained canonical?

3. Use Algorithm 7.1 to find an optimised ...