PROBLEMS AND EXERCISES

$7\mathrm{.}35$ Based on the information below, draw a context diagram

and a level$-0$ diagram for the entire system. In addition,

draw a level$-1$ diagram and a level$-2$ diagram for one part of

the system.

$-$A person sends a letter to another person using postal

services.

$-$The letter should be franked $($stamped$),$ sorted, and

delivered to the recipient.

$-$When a letter has been franked, it is noted in a table in

a database.

$-$A letter with an unreadable address is handled manually.