必要性是单纯矩阵A=∑lB1 A=∑4∑Bn令4=∑B A=∑4(3) Bii Blk Bi i=l,j=k 0i≠l或j≠k必要性 A是单纯矩阵  = = n i i Bi A l 1   = = = k i r j i i j i A B 1 1   = = i r j Ai Bij 1 令 (3) 1  = = k i A i Ai      = = = i l j k B i l j k B B i j i j l k 0 或