theorem Th5: :: JORDAN15:5

for G being Go-board
for i, j, k, j1, k1 being Nat st 1 <= i & i <= len G & 1 <= j & j <= j1 & j1 <= k1 & k1 <= k & k <= width G holds
LSeg ((G * (i,j1)),(G * (i,k1))) c= LSeg ((G * (i,j)),(G * (i,k)))