Explanation:The comparison operators are (<, ≤, =, =, >, ≥). 7. An expression in the domain relational calculus is of the form
A. {P(x1, x2, . . . , xn) | < x1, x2, . . . , xn > }
B. {x1, x2, . . . , xn | < x1, x2, . . . , xn > }
C. { x1, x2, . . . , xn | x1, x2, . . . , xn}
D. {< x1, x2, . . . , xn > | P(x1, x2, . . . , xn)}
Answer:A
Explanation:The comparison operators are (<, ≤, =, =, >, ≥). 7. An expression in the domain relational calculus is of the form
A. {P(x1, x2, . . . , xn) | < x1, x2, . . . , xn > } B. {x1, x2, . . . , xn | < x1, x2, . . . , xn > } C. { x1, x2, . . . , xn | x1, x2, . . . , xn} D. {< x1, x2, . . . , xn > | P(x1, x2, . . . , xn)}
Explanation:Here x1, x2, . . . , xn represent domain variables. P represents a formula composed of atoms, as was the case in the tuple relational calculus. 8. Find the names of all instructors in the Physics department together with the course id of all courses they teach: