WEBWe’ll see that to every root system there corresponds a semisimple Lie algebra, so it’s important to know all the root systems. Last time we saw the four series A r, B r, C r, and D r, and the three exceptions E 6, E 7, and E 8. The remaining two exceptions are F 4 and G 2, which we will describe in the following exercises. Exercise 17.1 ...