for f being FinSequence of (TOP-REAL 2)
for n, m, i being Nat
for G being Go-board st rng f misses rng (Col (G,i)) & f /. n in rng (Line (G,m)) & n in dom f & i in Seg (width G) & m in dom G & width G > 1 holds
f /. n in rng (Line ((DelCol (G,i)),m)) by MATRIX_0:75;