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GATE CSE 2026 Session 1 Q65: Number of superkeys with candidate keys {A,B} and {A,C}

Question

Consider a relational database schema with a relation R(A,B,C,D)R(A, B, C, D). If {A,B}\{A, B\} and {A,C}\{A, C\} are the only two candidate keys of the relation RR, then the number of superkeys of relation RR is ______. (answer in integer)

Try it: numerical answer: type the value

Numerical answer. No negative marking.
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Answer: 6 (official GATE 2026 final answer key)

Concept used: Superkeys are supersets of candidate keys; count with inclusion–exclusion.

First step: Supersets of AB: 22=42^2 = 4; supersets of AC: 4; supersets of ABC: 2; so 4+4−24 + 4 - 2.

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Source: official GATE 2026 Session 1 CS question paper and final answer key, organised by IIT Guwahati. Question paper · Answer key

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