September 12th:
It seems that you have some question about the database design, and it was true because of one mistake that I did.
So in order to solve this problem you just have to add one attribute in the Hall table: province.
Therefore the schema is:
City (name, province, country). The primary key of the relation is composed by City, Province.
Hall (name, city, province, capacity). Primary Key: name
Foreign Key (city, province) references the primary key in City (name, province)
Show (title, artist, hall, attendance) same that before.
We understand that you already answered some questions using the previous schema and positional notation in R.A, or R.C; so please write before each question the schema for the relation "Hall" that you used to avoid any confusions.
Sorry about that,
Laurent