DYNKIN DIAGRAMS

Classify simple Lie algebras — ADE classification and exceptional types
Properties:
Rank:
dim(g):
|Φ| roots:
|W| (Weyl):
Exponents:
Coxeter h:
Killing's classification (1888):
Every complex simple Lie algebra is one of:
Aₙ, Bₙ, Cₙ, Dₙ (n≥2), E₆, E₇, E₈, F₄, G₂

Cartan matrix:
Aᵢⱼ = 2⟨αᵢ,αⱼ⟩/⟨αⱼ,αⱼ⟩
Off-diagonal: 0,−1,−2,−3

Simply laced (all bonds single):
Aₙ, Dₙ, E₆, E₇, E₈

E₈ is special: 240 roots, dim=248, appears in string theory compactification