“…This can be thought of as the Fourier transform representation of the formulation we gave in Section 2. Recently this context has been used to prove interesting integrability results/connections for the cubic Szegö equation, see Pocovnicu [85], Grellier and Gerard [51] and Gerard and Pushnitski [49], and to extend regularity results for the Korteweg-de Vries equation, see Grudsky and Rybkin [52,53,54]. There is a natural decomposition L 2 (R) = H + ⊕ H − and thus an immediate direction to pursue would be to consider our Marchenko equation and Fredholm Grassmannian flow in this context and establish a connection to the results of, for example, Grellier and Gerard [51] and Grudsky and Rybkin [54].…”