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Find out the closure of attribute set (AG), i.e., (AG)+ in R. Set of FD’s are as given: R= {A,B,C,G,H,I}, F= {A → B,A → C,CG → H,B → H}. Is (AG) a super key of R?

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Ans

A → B, B → H, so A → H (Transitivity)

A → B, A → C, A → H, so A → BCH (union)

A → BCH, so A → ABCH (Reflexivity)

AG → ABCGH (Augmentation)

So, closure of AG is (AG)+ ={A,B,C,G,H}. No rule is applied to find the FD like AG → I. So, AG cannot be a super key.

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