The uniqueness of a certain generalized octagon of order (2,4)(2,4)

In the theory of generalized polygons, the question whether there exists a unique generalized octagon of order (2,4)(2,4) is still open. In this paper, we show the uniqueness of such a generalized octagon under an extra assumption. We give a computer-assisted proof for the fact that the Ree–Tits octagon of order (2,4)(2,4) is, up to isomorphism, the unique generalized octagon of order (2,4)(2,4) containing at least one suboctagon of order (2,1)(2,1).