theorem :: GOBOARD1:35

for G being Go-board
for f being FinSequence of (TOP-REAL 2) st f is_sequence_on G & f /. 1 in rng (Col (G,1)) & f /. (len f) in rng (Col (G,(width G))) & width G > 1 & 1 <= len f holds
ex g being FinSequence of (TOP-REAL 2) st
( g /. 1 in rng (Col ((DelCol (G,(width G))),1)) & g /. (len g) in rng (Col ((DelCol (G,(width G))),(width (DelCol (G,(width G)))))) & 1 <= len g & g is_sequence_on DelCol (G,(width G)) & rng g c= rng f )