# Tag Info

### "Functional dependencies" with cardinality constraints

After searching around for paper some more (unfortunately, I found nothing in Ling Liu, M. Tamer Özsu eds. Encyclopedia of Database Systems), I managed to find out that these dependencies are called ...
1 vote
Accepted

### Find number of candidate keys given non-trivial functional dependency X->Y, where X is some set of attributes and Y is some prime attribute

X -> Y non-trivial means that X does not include Y. Since ...
• 809
1 vote

### Functional dependencies on relational schema

I assume, by key, you mean the candidate key. Let's check whether V is a candidate key: closure(V) = {V, W, X, Y, Z} Hence, V is a candidate key. closure(W) = {W, V, X, Y, Z} Hence, W is also a ...
1 vote
Accepted

### Normal form after decomposition of a relation

I think you are wrong. Here is a rough sketch of a proof (by contradiction) that the original claim is true. Suppose that the claim is false: this means that R1 or R2 (or both) are not in 3NF. ...
• 809
1 vote

### Functional Dependencies

$R$ has only five non-trivial functional dependencies (FDs). No, $R$ has many more non-trivial FDs. For example, Since A-> BC and C -> F, we also have AC->BF, which is also a non-trivial FD ...
• 39.1k
1 vote
Accepted

### Given a relation and asked to enumerate all FD's and mark the trivial FD's

I suppose that in the exercise, the request “organize them accordingly to the LHS”, is just a request of sorting all the functional dependencies (maybe lexicographically) with respect first to the ...
• 809

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