Integrable Systems Seminar
Wednesday, February 27, 2002, 4:00pm, 120 Physics
Peter Miller (University of Michigan)
The Degree of Approximation of Analytic Functions by Solitons
Abstract:
The problem of approximating a given real analytic bell-shaped function A(x), x real, by semiclassical soliton ensembles is described. A semiclassical soliton ensemble is in this context a reflectionless potential of the nonselfadjoint Zakharov-Shabat operator with derivatives proportional to a small parameter hbar having approximately 1/hbar purely imaginary eigenvalues accumulating according to a Bohr-Sommerfeld quantization rule. In other words, it is a nonlinear superposition of stationary solitons. By means of a novel and rigorous asymptotic analysis of a matrix Riemann-Hilbert problem in the spirit of Deift and Zhou, it is shown that the approximation error is of the order of hbar^{1/7} pointwise in x.

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