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# Mathematical Research Letters

## Volume 6 (1999)

### Number 6

### Global wellposedness for KdV below ${L^2}$

Pages: 755 – 778

DOI: http://dx.doi.org/10.4310/MRL.1999.v6.n6.a13

#### Authors

#### Abstract

The initial value problem for the Korteweg-deVries equation on the line is shown to be globally wellposed for rough data. In particular, we show global wellposedness for certain initial data in $H^s$ for an interval of negative $s$. The proof is an adaptation of a general argument introduced by Bourgain to prove a similar result for a nonlinear Schrödinger equation. The proof relies on a generalization of the bilinear estimate of Kenig, Ponce and Vega.