theorem :: MATRTOP2:17

for n, m being Nat
for f being b₁ -element real-valued FinSequence
for M being Matrix of n,m,F_Real
for B being OrdBasis of Lin (lines M) st B = M holds
for Mf being Element of (Lin (lines M)) st Mf = (Mx2Tran M) . f holds
Mf |-- B = f