theorem Th18: :: GOBOARD7:18

for i, j being Nat
for G being Go-board st 1 <= i & i + 1 <= len G & 1 <= j & j + 1 <= width G holds
(LSeg ((G * (i,j)),(G * ((i + 1),j)))) /\ (LSeg ((G * ((i + 1),j)),(G * ((i + 1),(j + 1))))) = {(G * ((i + 1),j))}