To represent this process of inference symbolically we take the premise in the form

A = AB.(1)

We observe that by the Law of Duality the term not-B is thus described

b = Abab.(2)

For A in this proposition we substitute its description as given in (1), obtaining

b = ABbab.

But according to the Law of Contradiction the term ABb must be excluded from thought, or

ABb = 0.

Hence it results that b is either nothing at all, or it is ab; and the conclusion is

b = ab.