Question: Let R = (A, B, C), and let r1 and r2 both be relations on schema R. Give expressions in QBE, and Datalog equivalent to

Let R = (A, B, C), and let r1 and r2 both be relations on schema R. Give expressions in QBE, and Datalog equivalent to each of the following queries:

a. r1 ∪ r2

b. r1 ∩ r2

c. r1 − r2

d. IIAB (r1) 1 IIBC (r2)

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