Sharp thresholds for high-dimensional and noisy recovery of sparsity

By Martin J. Wainwright. 2006

239 citations recorded by the source corpus.

The problem of consistently estimating the sparsity pattern of a vector $\betastar \in \real^\mdim$ based on observations contaminated by noise arises in various contexts, including subset selection in regression, structure estimation in graphical models, sparse approximation, and signal denoising. We analyze the behavior of $\ell_1$-constrained quadratic programming (QP), also referred to as the Lasso, for recovering the sparsity pattern. Our main result is to establish a sharp relation between the problem dimension $\mdim$, the number $\spindex$ of non-zero elements in $\betastar$, and the number of observations $\numobs$ that are required for reliable recovery. For a broad class of Gaussian ensembles satisfying mutual incoherence conditions, we establish existence and compute explicit values of thresholds $\ThreshLow$ and $\ThreshUp$ with the following properties: for any $\epsilon > 0$, if $\numobs > 2 (\ThreshUp + \epsilon) \log (\mdim - \spindex) + \spindex + 1$, then the Lasso succeeds in recovering the sparsity pattern with probability converging to one for large problems, whereas for $\numobs < 2 (\ThreshLow - \epsilon) \log (\mdim - \spindex) + \spindex + 1$, then the probability of successful recovery converges to zero. For the special case of the uniform Gaussian ensemble, we show that $\ThreshLow = \ThreshUp = 1$, so that the threshold is sharp and exactly determined.

Subfields: Applied Mathematics, Computational Mechanics, Computer Vision and Pattern Recognition

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In Applied Mathematics

  1. Robert Tibshirani
  2. Cun-Hui Zhang
  3. Martin J. Wainwright
  4. Bin Yu
  5. Jinchi Lv
  6. Jian Huang
  7. Soumendra Nath Lahiri
  8. A. Chatterjee

In Computational Mechanics

  1. Martin J. Wainwright
  2. Cun-Hui Zhang
  3. Robert Tibshirani
  4. Tong Zhang
  5. Francis R. Bach
  6. E.J. Candes
  7. Bin Yu
  8. Jianqing Fan

In Computer Vision and Pattern Recognition

  1. Luc Van Gool
  2. Robert Tibshirani
  3. Lei Zhang
  4. Eric P. Xing
  5. Dacheng Tao
  6. Tong Zhang
  7. Ming-Hsuan Yang
  8. Trevor Darrell

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