Published online by Cambridge University Press: 20 November 2018
We prove simplicity for incomplete rank 2 Kac—Moody groups over algebraic closures of finite fields with trivial commutation relations between root groups corresponding to prenilpotent pairs. We don't use the (yet unknown) simplicity of the corresponding finitely generated groups (i.e., when the ground field is finite). Nevertheless we use the fact that the latter groups are just infinite (modulo center).
The first author was supported in part by Grant-in-aid for Science Research (Monkasho Kakenhi) in Japan. The second author was supported in part by the Institut Universitaire de France.