Why is the relational data model in the case study not normalized?
The data model is intended to show a realistic example or a data models which has optimizations, and which is not necessarily in 3NF or BCNF. The case study is intended to be a wide-ranging example from which submission authors can tackle what they consider to be the most interesting parts. Authors may wish to consider a simplified version of the relational data model, perhaps one that is fully normalized.