Question

A functional dependency f on R is _______  by a set of functional dependencies F on r if every instance of r(R) that satisfies f also satisfies F.

(a) Logically Defined

(b) Logically Derived

(c) Logically implied

(d) None of the mentioned

I have been asked this question in an interview for job.

The origin of the question is Functional-Dependency Theory in chapter Relational Database Design of RDBMS

Answer 1

Correct choice is (c) Logically implied

To explain: Given a set F of functional dependencies on a schema, we can prove that certain other functional dependencies also hold on that schema. We say such FDs are logically implied by F. A functional dependency f on R is logically implied by a set of functional dependencies F on r if every instance of r(R) that satisfies F also satisfies f.