Armstrong axioms. Suppose we have the following relation schema R and set of functional dependencies F:

R = (A, B, C, D, E, F, G) F = { A -> BC CD -> AB EF ->AD B -> AEF}

For each of the following, determine whether it is in F+ (i.e., can be derived from F). If the answer is yes, show how it can be derived step by step (and indicate which rule in Armstrong axioms is involved). If not, explain why.

(a) AD -> EF

(b)B -> CD

(c)DE -> AC

(d)CEF -> G