BCNF Boyce-Codd Normal Form
A relation schema R is in BCNF if it is in 3NF and accepts an additional constraint that for every FD X A, X has to be a candidate key. If a relational process is in BCNF then all redundancy based on functional dependency has been replaced, although other kinds of redundancy can still exist. A relational schema R is in Boyce-Codd normal form if and only if for each one of its dependencies X → Y.