Y=(A'+B+C+D)(A+B+C+D)(A+B+C'+D)
=[A'(B+C+D)+AA'+A(B+C+D)+(B+C+D)](A+B+C'+D)
=(B+C+D)(A+B+C'+D)
=A(B+D)+(B+D)+C'(B+D)+C(A+B+C'+D)
=(B+D)+C(A+B+C'+D)
=(B+D)+C(B+D)+AC+CC'
=B+D+AC
图就不画了