Which is the redundant relationship in this ER Diagram and why? Which is the redundant relationship in this ER Diagram and why? A few of my friends and I have been trying to figure it out but keep going in circles. 



where the attributes of each entity are as follows:

Employee: Employee_No, Name, Address and Telephone_No.
Department: Department_No, Name and Location.
Training Course: Course Code, Title, Start_Date and Description.
None of them are redundant. It's ok to have a loop. 

You seem to be missing a many-many relationship (Employee Course) table, though.