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Consider a relation schema r(ABCDEF) and attribute A is element of every candidate key of r. Maximum number of possible candidate keys of r is ________.

Thanku sir….

@Shreya2002 don’t call me sir ..I am a aspirant.😁

Thank you for the explanation ✅

Maximum number of candidate keys for a relation can be given by:$\binom{n}{\left \lceil n/2 \right \rceil}$. For example R(A,B,C,D) have AB,BC,CD,AD,BD .Here A is fixed in any candidate key, so for other 5 attributes we  have $\binom{5}{\left \lceil 5/2 \right \rceil} = 10$ keys. So, answer is 10.