Note that the ASSIGNMENT table stores the JOB$\_$CHG$\_$HOUR values as an attribute $($ASSIGN$\_$CHG$\_$HR$)$ to maintain historical accuracy of the data. The JOB$\_$CHG$\_$HOUR values are likely to change over time. In fact, a JOB$\_$CHG$\_$HOUR change will be reflected in the ASSIGNMENT table. Naturally, the employee primary job assignment might also change, so the ASSIGN$\_$JOB is also stored. Because those attributes are required to maintain the historical accuracy of the data, they are not redundant.