A: Find closure of AB in Relation ( A, B, C, D, E, F ): 55

Given Relation:

U = (A, B, C, D, E, F)

Given Functional Dependencies:

AB → C
B → E
CF → D

 

Closure of AB

{AB}+ = {AB} (axiom of reflexivity)

      = {ABC} (AB → C, given FD)

      = {ABCE} (B → E, given FD)

 

The closure of AB is:

{AB}+ = {ABCE}