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.

Background

The thesis relates crystallographic Coxeter-Dynkin diagrams to infinite Kac--Moody algebras and notes that known classifications cover important subclasses, including the hyperbolic cases. However, the full classification of crystallographic Coxeter groups and the corresponding Kac--Moody structures is not complete.

This classification problem is relevant to identifying possible Lorentzian lattices and symmetry groups that could support generalized spacetime quasicrystals.

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'