Determine whether hyperbolic non-crystallographic groups embed into crystallographic partners
Determine whether any known non-crystallographic hyperbolic Coxeter group can be embedded as a subgroup of a higher-rank crystallographic hyperbolic Coxeter group of the same general type, thereby forming a hyperbolic Coxeter pair.
References
On the other hand, even though several examples of non-crystallographic hyperbolic Coxeter groups are known in the literature, it is not known if any of them can be embedded into a higher-rank crystallographic group of the same nature to form a hyperbolic Coxeter pair.
— Spacetime Quasicrystals and Computational Complexity Theory in the Road Towards Quantum Gravity
(2610.09855 - Mygdalas, 7 Oct 2026) in Chapter 7, Section 7.1, 'Revisiting the Non-Crystallographic Symmetry'