let M be Go-board; for f being S-Sequence_in_R2 st f is_sequence_on M holds
for p being Point of (TOP-REAL 2) st p in rng f holds
L_Cut (f,p) is_sequence_on M
let f be S-Sequence_in_R2; ( f is_sequence_on M implies for p being Point of (TOP-REAL 2) st p in rng f holds
L_Cut (f,p) is_sequence_on M )
assume A1:
f is_sequence_on M
; for p being Point of (TOP-REAL 2) st p in rng f holds
L_Cut (f,p) is_sequence_on M
let p be Point of (TOP-REAL 2); ( p in rng f implies L_Cut (f,p) is_sequence_on M )
assume
p in rng f
; L_Cut (f,p) is_sequence_on M
then
L_Cut (f,p) = mid (f,(p .. f),(len f))
by Th37;
hence
L_Cut (f,p) is_sequence_on M
by A1, JORDAN1H:27; verum