Hi, I'm working on a project where I have to do normal forms 1 to 5, I'm really new at this and I'm not sure I understand these:

1. {A,B} -> C and {A,C} -> B but B doesn't -> C and C doesn't -> B. {A,B} and {A,C} are candidate keys in relation (A,B,C,D).
Is this in Boyce-Codd normal form or not?

2. Is NF4 only about multiple attributes (as in, if I have tuples (a,b,c) and (a,d,e) I also have (a,b,e) and (a,d,c))?

3. If I have columns A,B,C,D and A,B,C (together) make up the primary key, is this in BCNF, NF4 and NF5? (C is actually an attribute in the relation between A and B not another entity but D depends on A,B /and/ C)
What about if I have columns A,B,C with A,B making up the primary key?

Help please!