Consider a relation R(A, B, C, D, E) with the following three functional dependencies. AB C; BC D; C E; The number of superkeys in the relation R is _____________.

GATE CSE 2022 Q31: Number of superkeys of R(A, B, C, D, E) with three FDs

Consider a relation $R(A, B, C, D, E)$ with the following three functional dependencies.

$AB \to C$ ; $BC \to D$ ; $C \to E$ ;

The number of superkeys in the relation R is _____________.

Try it: numerical answer: type the value

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Numerical answer. No negative marking.

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Answer: 8 (official GATE 2022 final answer key)

Concept used: Attributes that never appear on a right side must be in every key; superkeys are supersets of candidate keys.

First step: A and B never appear on the right, so check whether $AB^+$ is all of $R$ ; then count supersets of $AB$ .

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Source: official GATE 2022 CS question paper and final answer key, organised by IIT Kharagpur. Question paper · Answer key