For rank 3 Coxeter groups, [ p,3], there is a trionic subgroup [ p,3 ] ≅ [ p /2, p ], or = . For example, the finite group [4,3 ] ≅ [2,4], and Euclidean group [6,3 ] ≅ [3,6], and hyperbolic group [8,3 ] ≅ [4,8].