Remark on Well-posedness of Quadratic Schrodinger equation with nonlinearity $ubar u$ in $H^{-1/4}(R)$

In this remark, we give another approach to the local well-posedness of quadratic Schrodinger equation with nonlinearity $ubar u$ in $H^{-1/4}$, which was already proved by Kishimoto cite{kis}. Our resolution space is $l^1$-analogue of $X^{s,b}$ space with low frequency part in a weaker space $L^{infty}_{t}L^2_x$. Such type spaces was developed by Guo. cite{G} to deal the KdV endpoint $H^{-3/4}$ regularity.