Our main results are summarized below.

The regularizer P λi|b|(i) is a sorted `1-norm (denoted asJλ(b) henceforth), which isnon-separabledue to the sorting operation involved in its calculation.

We consider the problem of estimating a rank-1 signal from a noisy data matrix.

We propose an orthogonal approximate message passing (OAMP) algorithm for signal estimation in the rectangular spiked matrix model with general rotationally invariant (RI) noise. We establish a rigorous state evolution that exactly characterizes the high-dimensional dynamics of the algorithm. Building on this framework, we derive an optimal variant of OAMP that minimizes the predicted mean-squared error at each iteration. For the special case of i.i.d. Gaussian noise, the fixed point of the proposed OAMP algorithm coincides with that of the standard AMP algorithm. For general RI noise models, we conjecture that the optimal OAMP algorithm is statistically optimal within a broad class of iterative methods, and achieves Bayes-optimal performance in certain regimes.

Signal recovery under generative neural network priors has emerged as a promising direction in statistical inference and computational imaging. Theoretical analysis of reconstruction algorithms under generative priors is, however, challenging. For generative priors with fully connected layers and Gaussian i.i.d.

AMP to get insights into the statistical properties of SLOPE.

For generative priors with fully connected layers and Gaussian i.i.d.