Lax 1968 (Comm. Pure Appl. Math. 21:467) introduced the paired-operator framework [L, M] = ∂_t L to prove integrability of the KdV equation. L = -∂² + u is a Schrödinger operator whose potential u(x,t) evolves according to KdV; M = -4∂³ +…
Lax 1968 (Comm. Pure Appl. Math. 21:467) introduced the paired-operator framework [L, M] = ∂_t L to prove integrability of the KdV equation. L = -∂² + u is a Schrödinger operator whose potential u(x,t) evolves according to KdV; M = -4∂³ +…