How do I determine if the following relation is in BCNF form?
R(U,V,W,X,Y,Z)
UVW ->X
VW -> YU
VWY ->Z
I understand that for a functional dependency A->B A must be a superkey. And the relation must be in 3NF form. But I am unsure how to apply the concepts.
To determine if a relation is in BCNF, for the definition you should check that for each non-trivial dependency in F+
, that is, for all the dependencies specified (F
) and those derived from them, the determinant should be a superkey. Fortunately, there is a theorem that says that it is sufficient perform this check only for the specified dependencies.
In your case this means that you must check if UVW
, VW
and VWY
are superkeys.
And to see if in a dependency X -> Y
the set attributes X
is a superkey you can compute the closure of the attributes (X+
) and check if it contains the right hand part Y
.
So you have to compute UVW+
and see if it contains {U,V,W,X,Y,Z}
and similarly for the other two dependencies. I leave to you this simple exercise.