00 11 01 10 00 11 11 01 01 10 10 00 ba b 00 1 11 0 01 1 10 0 ba a 00 1 11 1 01 0 10 0 ba b 00 1 01 1 ba a 00 1 11 1 a := (a and b) or (not a and not b) b := not b