F₄ T action
f₄_T_action
Plain-language statement
f₄ transforms under T as f₄|T = f₃. Proof outline: 1. (serre_D 2 H₄)|[4]T = serre_D 2 (H₄|[2]T) = serre_D 2 H₃ 2. (H₄(2H₂ + H₄))|[4]T = H₃(2(-H₂) + H₃) = H₃(H₃ - 2H₂) Using Jacobi H₃ = H₂ + H₄: H₃ - 2H₂ = H₄ - H₂ 3. f₄|[4]T = serre_D 2 H₃ + (1/6)H₃(H₃ - 2H₂) But H₂² - H₄² = (H₂ - H₄)(H₂ + H₄) = (H₂ - H₄)H₃ So (1/6)(H₂² - H₄²) = -(1/6)H₃(H₄ - H₂) = -(1/6)H...
Source project: Sphere Packing in Dimension 8
Person-level attribution pending.