I have the following problem:

AB -> CD
H->B
G ->DA
CD-> EF
A -> HJ
J>G

I understand the first step (break down right hand side) and get the following results:

AB -> C
AB -> D
H -> B
G -> D
G -> A
CD -> E
CD -> F
A -> H
A -> J
J -> G

I understand that A -> h and h -> b, therefore I can remove the B from AB -> c and ab -> D, to get:

A -> C
A -> D
H -> B
G -> D
G -> A
CD -> E
CD -> F
A -> H
A -> J
J -> G

The step that follows is what I can't compute (reduce the left hand side)

Any help will be greatly appreciated.