# Difference between revisions of "Modified Korteweg-de Vries on T"

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* C^0 LWP in L^2 in the defocusing case [KpTp-p2] | * C^0 LWP in L^2 in the defocusing case [KpTp-p2] | ||

** C^0 LWP in <span class="SpellE">H^s</span> for s > 3/8 [Takaoka and <span class="SpellE">Tsutsumi</span>?]Note one has to gauge away a nonlinear resonance term before one can apply iteration methods. | ** C^0 LWP in <span class="SpellE">H^s</span> for s > 3/8 [Takaoka and <span class="SpellE">Tsutsumi</span>?]Note one has to gauge away a nonlinear resonance term before one can apply iteration methods. | ||

− | ** Analytic LWP in <span class="SpellE">H^s</span> for s >= 1/2, in both focusing and defocusing cases [[ | + | ** Analytic LWP in <span class="SpellE">H^s</span> for s >= 1/2, in both focusing and defocusing cases [[Bibliography#KnPoVe1993|KnPoVe1993]], [[Bibliography#Bo1993b|Bo1993b]]. |

− | ** This is sharp in the sense of analytic well-<span class="SpellE">posedness</span> [[ | + | ** This is sharp in the sense of analytic well-<span class="SpellE">posedness</span> [[Bibliography#KnPoVe1996|KnPoVe1996]] or uniform well-<span class="SpellE">posedness</span> [<span class="SpellE">CtCoTa</span>-p] |

* C^0 GWP in L^2 in the defocusing case [KpTp-p2] | * C^0 GWP in L^2 in the defocusing case [KpTp-p2] | ||

− | ** Analytic GWP in <span class="SpellE">H^s</span> for s >= 1/2<span class="GramE"> [</span>[ | + | ** Analytic GWP in <span class="SpellE">H^s</span> for s >= 1/2<span class="GramE"> [</span>[Bibliography#CoKeStTaTk-p2 |CoKeStTkTa-p2]], via the <span class="SpellE">KdV</span> theory and the Miura transform, for both the <span class="SpellE">focussing</span> and <span class="SpellE">defocussing</span> cases. |

− | ** Was proven for s >= 1 in [[ | + | ** Was proven for s >= 1 in [[Bibliography#KnPoVe1993|KnPoVe1993]], [[Bibliography#Bo1993b|Bo1993b]]. |

− | ** One has GWP for random data whose Fourier coefficients decay like 1/|k| (times a Gaussian random variable) [[ | + | ** One has GWP for random data whose Fourier coefficients decay like 1/|k| (times a Gaussian random variable) [[Bibliography#Bo1995c|Bo1995c]]. Indeed one has an invariant measure. Note that such data barely fails to be in H<span class="GramE">^{</span>1/2}, however one can modify the local well-<span class="SpellE">posedness</span> theory to go below H^{1/2} provided that one has a decay like O(|k|^{-1+\eps}) on the Fourier coefficients (which is indeed the case almost surely). |

[[Category:Integrability]] | [[Category:Integrability]] | ||

[[Category:Airy]] | [[Category:Airy]] | ||

[[Category:Equations]] | [[Category:Equations]] |

## Revision as of 16:10, 31 July 2006

The local and global well-posedness theory for the modified Korteweg-de Vries equation on the torus is as follows.

- Scaling is s_c = -1/2.
- C^0 LWP in L^2 in the defocusing case [KpTp-p2]
- C^0 LWP in H^s for s > 3/8 [Takaoka and Tsutsumi?]Note one has to gauge away a nonlinear resonance term before one can apply iteration methods.
- Analytic LWP in H^s for s >= 1/2, in both focusing and defocusing cases KnPoVe1993, Bo1993b.
- This is sharp in the sense of analytic well-posedness KnPoVe1996 or uniform well-posedness [CtCoTa-p]

- C^0 GWP in L^2 in the defocusing case [KpTp-p2]
- Analytic GWP in H^s for s >= 1/2 [[Bibliography#CoKeStTaTk-p2 |CoKeStTkTa-p2]], via the KdV theory and the Miura transform, for both the focussing and defocussing cases.
- Was proven for s >= 1 in KnPoVe1993, Bo1993b.
- One has GWP for random data whose Fourier coefficients decay like 1/|k| (times a Gaussian random variable) Bo1995c. Indeed one has an invariant measure. Note that such data barely fails to be in H^{1/2}, however one can modify the local well-posedness theory to go below H^{1/2} provided that one has a decay like O(|k|^{-1+\eps}) on the Fourier coefficients (which is indeed the case almost surely).