Liouville Integrability — Toda Lattice

N particles on a ring with exponential interactions — N conserved quantities in involution

Toda Lattice

Total energy H:
Momentum P:
I₂ (2nd integral):
I₃ (3rd integral):
dH/H₀:
Toda lattice (1967): V(r) = e^(-r) + r
H = Σpᵢ²/2 + Σe^(qᵢ₊₁-qᵢ)

Flaschka variables:
aₙ = ½e^(-(qₙ₊₁-qₙ)/2)
bₙ = -pₙ/2

Isospectral flow: dL/dt = [B,L]
Lax pair → N conserved Iₖ = tr(Lᵏ)

Arnold-Liouville: compact level sets = tori, action-angle variables exist.