theorem Th67: :: MATRIX_0:67

for D being non empty set
for G being Matrix of D
for i, k, m being Nat st i in Seg (width G) & width G = m + 1 & m > 0 & 1 <= k & k < i holds
( Col ((DelCol (G,i)),k) = Col (G,k) & k in Seg (width (DelCol (G,i))) & k in Seg (width G) )