Classify crystallographic Coxeter and Kac--Moody structures
Classify the general family of crystallographic Coxeter groups, including the associated infinite Kac--Moody structures, beyond the subclasses already classified.
References
Their general classification is still an open problem, but the ``hyperbolic'' ones (not ultra non-compact) have been classified in ; they exist up to dimension 10 again and the nicest one is $E_{10}$, which has been shown to contain all the other ones as its subalgebras .
— Spacetime Quasicrystals and Computational Complexity Theory in the Road Towards Quantum Gravity
(2610.09855 - Mygdalas, 7 Oct 2026) in Chapter 2, Section 2.1, 'Coxeter Theory'