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arXiv · 1105.3601

Sharp ill-posedness results for the KdV and mKdV equations on the torus

Luc Molinet
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Abstract

We establish a new a priori bound for $ L^2 $-bounded sequences of solutions to the mKdV equations on the torus. This first enable us to construct weak solutions in $ L^2$ for this equation and to check that the "solutions" constructed by Kappeler and Topalov in the defocusing case satisfy the equation in some weak sense. In a second time, we prove that the solution-map associated with the mKdV and the KdV equation are discontinuous for the $ H^s(\T) $ topology for respectively $ s<0$ and $ s<-1$. These last results are sharp.

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Luc Molinet. 2011-05-18. Sharp ill-posedness results for the KdV and mKdV equations on the torus. https://arxiv.org/abs/1105.3601

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