let f be FinSequence of (TOP-REAL 2); :: thesis: for i, n, m being Element of 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))

let i, n, m be Element of NAT ; :: thesis: 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))

let G be Go-board; :: thesis: ( 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 implies f /. n in rng (Line ((DelCol (G,i)),m)) )
set D = DelCol (G,i);
assume that
A1: rng f misses rng (Col (G,i)) and
A2: f /. n in rng (Line (G,m)) and
A3: n in dom f and
A4: i in Seg (width G) and
A5: m in dom G and
A6: width G > 1 ; :: thesis: f /. n in rng (Line ((DelCol (G,i)),m))
A7: ( len (Line ((DelCol (G,i)),m)) = width (DelCol (G,i)) & dom (Line ((DelCol (G,i)),m)) = Seg (len (Line ((DelCol (G,i)),m))) ) by FINSEQ_1:def 3, MATRIX_1:def 8;
consider j being Nat such that
A8: j in dom (Line (G,m)) and
A9: f /. n = (Line (G,m)) . j by A2, FINSEQ_2:11;
reconsider j = j as Element of NAT by ORDINAL1:def 13;
A10: len (Line (G,m)) = width G by MATRIX_1:def 8;
then A11: j <= width G by A8, FINSEQ_3:27;
A12: dom (Line (G,m)) = Seg (len (Line (G,m))) by FINSEQ_1:def 3;
then A13: 1 <= i by A4, A10, FINSEQ_3:27;
A14: f /. n = G * (m,j) by A8, A9, A12, A10, MATRIX_1:def 8;
A15: i <= width G by A4, A12, A10, FINSEQ_3:27;
A16: 1 <= j by A8, FINSEQ_3:27;
consider M being Element of NAT such that
A17: width G = M + 1 and
A18: M > 0 by A6, SEQM_3:83;
A19: width (DelCol (G,i)) = M by A4, A17, A18, Th26;
per cases ( j < i or i < j ) by A1, A3, A5, A14, Th24, XXREAL_0:1;
suppose A20: j < i ; :: thesis: f /. n in rng (Line ((DelCol (G,i)),m))
then j < width G by A15, XXREAL_0:2;
then j <= M by A17, NAT_1:13;
then A21: j in Seg (width (DelCol (G,i))) by A16, A19, FINSEQ_1:3;
f /. n = (DelCol (G,i)) * (m,j) by A4, A5, A14, A16, A17, A18, A20, Th31;
then (Line ((DelCol (G,i)),m)) . j = f /. n by A21, MATRIX_1:def 8;
hence f /. n in rng (Line ((DelCol (G,i)),m)) by A7, A21, FUNCT_1:def 5; :: thesis: verum
end;
suppose A22: i < j ; :: thesis: f /. n in rng (Line ((DelCol (G,i)),m))
reconsider l = j - 1 as Element of NAT by A16, INT_1:18;
A23: l <= M by A11, A17, XREAL_1:22;
i + 1 <= j by A22, NAT_1:13;
then A24: i <= l by XREAL_1:21;
then 1 <= l by A13, XXREAL_0:2;
then A25: l in Seg (width (DelCol (G,i))) by A19, A23, FINSEQ_1:3;
l + 1 = j ;
then f /. n = (DelCol (G,i)) * (m,l) by A4, A5, A14, A13, A17, A24, A23, Th32;
then (Line ((DelCol (G,i)),m)) . l = f /. n by A25, MATRIX_1:def 8;
hence f /. n in rng (Line ((DelCol (G,i)),m)) by A7, A25, FUNCT_1:def 5; :: thesis: verum
end;
end;