# Stupid/ simple question about g2

1. Nov 14, 2007

### Jim Kata

I really don't know that much representation theory or group theory.

I was looking at Garrett lisi's presentation, and I was looking at the 3d root system of g2. It struck me that it looked similar to a dodecahedron inscribed in a cube. Now, I do know that the dodecahedron group, and the cube group are dual. Can g2 be broken up into the symmetries of a cube, and a dodecahedron?

2. Nov 15, 2007

### Jim Kata

I meant dual Octahedron is dual to the cube. sorry

3. Nov 23, 2007

### Chris Hillman

The Root System G_2

Unless I misunderstand what you are talking about, I think you mean 2d; see James E. Humphreys, Introduction to Lie Algebras and Representation Theory, Springer, 1972, Fig. 1 on p. 44, for a picture of the root system $G_2$.