Question

GreenRecycle.com is a recycle firm whose main business is recycling paper. There is a particular standard to grade the recycled papers in the firm, which grades the papers as P11, P12, P13, P21, P22, P31 and P32.

a) Model the set of the papers
b) Three warehouses are used to store the papers and special accounts are assigned to the warehouses as given by:
warehouse = { X, Y, Z }
Account_warehouse = { (123,X), (456,Y), (789,Z) }

If the papers being stored in the warehouse are given as:
paper_warehouseAccount = { (P11,123), (P12,123), (P13,456), (P21,789), (P22,789), (P31,789), (P32,123) }

Find the papers stored in warehouse A.