Differential equations on Lie groups and tori, the wave equations and Huygens' principle
This note shows how a differential equation on a compact Lie group may be transferred to another equation on the maximal torus. Then the method is applied to wave equations. This makes easy to prove the non-existence of Huyghens' principle for the wave equations and its existence for the shifted Laplacian in odd dimensional spaces.
scientific article; zbMATH DE number 3927252