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I am trying to find the superkeys of this relation, but I am having troubles finding out how many superkeys there are and exactly what they are. I figured out that the candidate keys were {A},{B},{C},{D}.

Here is the relation:

R(A,B,C,D)

Functional Dependencies: 

A->B
B->C
C->D
D->A

Candidate keys: {A},{B},{C},{D} (from what I figured out)

Can someone please help me find the superkeys, and how exactly to find them?

Jordan Thornley
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1 Answers1

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Let me keep it simple: Here is a definition for super key and candidate key:

Super Key

Super key stands for superset of a key.

A Super Key is a set of one or more attributes that are taken collectively and can identify all other attributes uniquely.

Candidate Keys

Candidate Keys are super keys for which no proper subset is a super key. In other words candidate keys are minimal super keys.

Thus,any combination of candidate keys with other keys is a super key

In this example, any combination of candidate keys of A,B,C,D is a Super key

Hope this helps!

Community
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Lordferrous
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