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.

Estimating a vector x from noisy linear measurements Ax + w often requires use of prior knowledge or structural constraints on x for accurate reconstruction. Several recent works have considered combining linear least-squares estimation with a generic or "plug-in" denoiser function that can be designed in a modular manner based on the prior knowledge about x.

Consider x Rd an input signal, which we can think of as a grayscale pixel representation of an image.

Here, the functionf() is applied toAx in a component-wise manner. The above model arises in many applications of signal processing [13, 10, 41], communications [56, 9, 25], and machine learning [48, 40].

We establish Central Limit Theorems (CLT) for the derivatives of 2-layers NN models in(2) when n,p,d + in the proportional asymptotic regime(6). A weighted average of the gradients of the trained NN, up to an explicit additive correction, is proved to be asymptotically normal, where the variance of the limit can be estimatedexplicitly.

Similarly the ISOMAP face database consists ofimages (256levels ofgray)ofsize64 64,i.e.,vectors in R4096, whereas the correct intrinsic dimension is only3 (for the vertical, horizontal pause and lightingdirection). The second approach, is anaverage caseapproach (in the spirit of thestatistical mechanics treatment ofhighdimensional systems), thatmodelsfeaturevectorsby arandom ensemble,taken as aset ofrandom vectors with independently identically distributed (i.i.d.) components, and a small but xed fraction of non-zero components.

Similarly the ISOMAP face database consists ofimages (256levels ofgray)ofsize64 64,i.e.,vectors in R4096, whereas the correct intrinsic dimension is only3 (for the vertical, horizontal pause and lightingdirection). The second approach, is anaverage caseapproach (in the spirit of thestatistical mechanics treatment ofhighdimensional systems), thatmodelsfeaturevectorsby arandom ensemble,taken as aset ofrandom vectors with independently identically distributed (i.i.d.) components, and a small but xed fraction of non-zero components.

Data clustering is a widely used primitive in exploratory data analysis and summarization.