theorem Th19: :: MATRIX15:19

for k, m, n being Nat
for D being non empty set
for A being Matrix of n,m,D
for B being Matrix of n,k,D holds
( Segm ((A ^^ B),(Seg n),(Seg (width A))) = A & Segm ((A ^^ B),(Seg n),((Seg ((width A) + (width B))) \ (Seg (width A)))) = B )