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Consider the representation of a ternary relationship using binary relationships
as described in this book and illustrated in Figure (b) (attributes
not shown)

a. Show a simple instance of E, A, B,C, RA, RB, and RC that cannot
correspond to any instance of A, B,C, and R.


b. Modify the E-R diagram of Figure (b) to introduce constraints that
will guarantee that any instance of E, A, B, C, RA, RB, and RC that
satisfies the constraints will correspond to an instance of A, B, C, and
R.


c. Modify the translation above to handle total participation constraints
on the ternary relationship.


d. The above representation requires that we create a primary-key attribute
for E. Show how to treat E as a weak entity set so that a
primary-key attribute is not required.

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