Coxeter did amazing stuff in higher-dimensional geometry. https://en.wikipedia.org/wiki/Harold_Scott_MacDonald_Coxeter https://en.wikipedia.org/wiki/Harold_Sco

Coxeter did amazing stuff in higher-dimensional geometry. https://en.wikipedia.org/wiki/Harold_Scott_MacDonald_Coxeter https://en.wikipedia.org/wiki/Harold_Scott_MacDonald_Coxeter I have one of his books about polytopes and find it hard to wrap my head around the details, despite a childhood interest in higher dimensions. The diagrams are terrific!