Wang’s Method (Cont.)
Transform each sequent until it is either an “axiom” and is proved, or it cannot be further transformed.
Note: Each rule removes one instance of a logical connective.
And on the left: X, A & B, Y => Z
Or on the right: X => Y, A v B, Z
Not on the left: X, ~A, Y => Z becomes X, Y => Z, A
Not on the right: X => Y, ~A, Z becomes X, A => Y, Z