{1}-逆与{1,2,3}-逆、{1,2,04}-逆 YeA{→rankY≥rankA rankY=rankA rankY=rank (A"A)A#s rank A"-rankA Y∈A{1,2} AY-(UHAHA)(AHA)DAH-UHAHA (AHA)AHAU =U(ABA)U=(AY)H) Y∈A{3} Y∈A{1,2,3} lexu@mail.xidian.edu.cn 矩阵论 30 lexu@mail.xidian.edu.cn