theorem :: ZMODLAT2:51

for n, i, j, k, m being Nat
for M being Matrix of n + 1,F_Real st 0 < n & M is Matrix of n + 1,F_Rat & [i,j] in Indices M & [k,m] in Indices (Delete (M,i,j)) holds
(Delete (M,i,j)) * (k,m) is Element of F_Rat