注：A表示非A
原式 = ABC + A(BC + B + C) + B + C 注：BC + B + C = 1
= ABC + A)BC + A)(~B + C) + B + C
= BC + B + C + A)(~B + C)
= BC + B(C + C) + C + A)(~B + C)
= BC + BC + C + C + A)(~B + C)
= C + C + C + A)(~B + C)
= 1 + C + A)(~B + C)
= 1