!x1*!x3+!x1*!x2+x1*x2*x3 = !x1(!x3+!x2) + x1*x2*x3 = !x1(!x2+!x3) + x1*x2*x3 = !x1(!(x2*x3)) + x1*x2*x3 = !(!x1 * !(x2*x3) * !(x1*x2*x3))
!x1*!x3+!x1*!x2+x1*x2*x3 = !x1(!x3+!x2) + x1*x2*x3 = !x1(!x2+!x3) + x1*x2*x3 = !x1(!(x2*x3)) + x1*x2*x3 = !(!x1 * !(x2*x3) * !(x1*x2*x3))