theorem
for
i being
Nat for
G being
Go-board st 1
< width G & 1
<= i &
i + 1
< len G holds
LSeg (
(((1 / 2) * ((G * (i,1)) + (G * ((i + 1),1)))) - |[0,1]|),
(((1 / 2) * ((G * ((i + 1),1)) + (G * ((i + 2),1)))) - |[0,1]|))
c= ((Int (cell (G,i,0))) \/ (Int (cell (G,(i + 1),0)))) \/ {((G * ((i + 1),1)) - |[0,1]|)}