(2)P(s)Q)左互质,P(s),R(s)非右互质 P(S,R(s)有非单模的gcrd,设为F(s),必非奇 P(S=P(SF(S) R(S=RSF(S) P(s),R(s)右互质 原描述可写成 P(SF(SE(s=Q(S)u(s) y(S)=R(SF(SS(S)+w(s)u(s) 设5(s)=F(S)(S),则 P(ss(s=Q(S)u(s) y(s)=R(SS(S)+w(s)u(s 不可简约 rnkP(s)]=mnk()s)]故P(Qs)左互质(2) P(s),Q(s)左互质，P(s),R(s)非右互质 P(s),R(s)有非单模的gcrd, 设为F(s), 必非奇  ( ) ( )  ( ) ( ), ( ), ( ) . ( ) ( ) ( ) ~ ( ) ( ) ( ) ( ) ( ) ~ ( ) ( ) ( ) ( ), ~ ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ), ( ) ( ) ( ) ( ) ( ) ( ) ( ) 故 左互质 不可简约 设 则 原描述可写成 右互质 rank P s Q s rank P s Q s P s Q s y s R s s W s u s P s s Q s u s s F s s y s R s F s s W s u s P s F s s Q s u s P s R s R s R s F s P s P s F s =     = + = =    = + = = =      