Before revision:  Namely, if the input model supports efficient \ell_2-norm importance sampling, and given A \in C^{m\times n} with minimum singular value \sigma and  b \in C^m as input , we can output a description of an x  such that \|x -
After revision:  Namely, given an A \in C^{m\times n} with minimum singular value \sigma and b \in C^m as input , we can output a description of an x such that \|x -