Unbounded Hankel operators and the flow of the cubic Szegő equation (2206.11543v2)

Abstract: We prove that, for any Hankel operator with a symbol from the Hardy class $H^2$, the maximal and minimal domains coincide. As an application, we prove that the evolution flow of the cubic Szeg\H{o} equation on the unit circle can be continuously extended to the whole class $H^2$.