functional dependency

Boyce/Codd Normal Form (BCNF)

In my article on 3NF we saw that it was the same as 2NF but with one additional restriction. BCNF, similarly, is 3NF with one more restriction:

“Relvar R is in Boyce/Codd normal form (BCNF) if and only if, for every nontrivial FD XY that holds in R, X is a superkey.”
Date, C.J. Database Design & Relational Theory. Sebastopol: O,Reilly Media, Inc., 2012. Print. (Emphasis theirs)