Application Techniques of Curtis-Tits-Phan to when is Even and Identifying these Groups by Free Amalgamated Product of Low Rank Subgroups, for some

Techniques of Curtis-Tits-Phan theory, have been applied to some groups of Lie-type and Kak-Moody type now. But has not applied to orthogonal groups in even characteristic. In this paper, we applied the techniques of Curtis-Tits-Phan theory to when is even. Specifically, we have identified these groups by free amalgamated products of low ranks subgroups when.