A college runs many evening classes (e.g. metalwork, pottery, art, local history). Each class may be taught by several teachers, and a teacher may teach several classes. A particular class always uses...

A college runs many evening classes (e.g. metalwork, pottery, art, local history). Each class may be taught by several teachers, and a teacher may teach several classes. A particular class always uses the same room (e.g. pottery always uses room R12). Because classes may meet at different times or on different evenings it is possible for different classes to share a room (e.g. pottery and art both use room R12).

(a) Draw an entity-relationship type diagram showing the entity types Teacher, Class, Room and the relationship types Teacher Class and Room Class.

(b) Re-draw your type diagram, decomposing any many:many relationship into 1:many relationships.