Functional Dependency

Question

How can we write dependency AB -> A ?

can we write it as B->A ??

Comments

if B --> A, then you can write it as AB --> A ( By augimenting A both side )

But if you have, AB --> A, then we can't say that it can be written as B ---> A or not? ( i mean it's depend upon your Functional dependency set)

 

For example,

if your FD set { AB --> A, B --> D and D --> A } then AB --> A can be written as B --->A ( i just removed redundant term. )

 

if your FD set { AB --> A, B --> D } then AB --> A can't be written as B --->A

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I have this FD set {AB->CDE, C->A, D->E}.

i have reduced this set to {AB->C, AB->D, C->A, D->E} by removing AB->E

Can this be reduced further ???

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No, it can't reduce further.