In Fig. 11–30, there is no explicit invariant that states that a Transaction cannot be linked to movements that are linked to the same account, because the structure of the model already demands is. Why is it not necessary?

Transcribed Image Text:

Account 2 Movement 1 | < > +name: String +value: Integer 1 +/balance: Integer = entry->sum(value) Transaction {movement->sum(value) = 0} | < > +name: String