In-place Value Permutation

The following properties are valid:

(X?Y)?Y = X

(X?Y)?X= Y

= XY’Y’ + X’YY’ + ((XY’)’(X’Y)’)Y

= XY’ + 0 + ((X’+Y)•(X+Y’))Y

= XY’ + X’XY + X’Y’Y +XYY + YY’Y

= XY’ + 0 + 0 + XY + 0

= X(Y’ + Y)

= X•1

= X