MINIMAL COVER OF FUNCTIONAL DEPENDENCIES

A minimal cover of a set of FDs F is a minimal set of functional dependencies Fmin that is equivalent to F.

There can be many such minimal covers for a set of functional dependencies F.

Steps to derive  minimal cover for  a FD set .

1)Right Hand Side (RHS) of all FDs should be single attribute .

2)Eliminate redundant functional dependencies if any .

Given relation R(A,B,C)    and     FDs : {  AB -> C, C -> A }   FDmin={ABàC}   ,here C-->A is  redundant dependency 

3)Remove redundant attribute on LHS if any .

 Consider  FD ,  AB -> C  

           If AB+ = A+  we can say B is redundant  then reduce to  AàC

 

           If AB+ =B+ we can say A is redundant then reduce to BàC