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[2205.06738] Sparsity and $\ell_p$-Restricted Isometry

 2 years ago
source link: https://arxiv.org/abs/2205.06738
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[Submitted on 13 May 2022]

Sparsity and ℓp-Restricted Isometry

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A matrix A is said to have the ℓp-Restricted Isometry Property (ℓp-RIP) if for all vectors x of up to some sparsity k, ∥Ax∥p is roughly proportional to ∥x∥p. It is known that with high probability, random dense m×n matrices (e.g., with i.i.d.\ ±1 entries) are ℓ2-RIP with k≈m/logn, and sparse random matrices are ℓp-RIP for p∈[1,2) when k,m=Θ(n). However, when m=Θ(n), sparse random matrices are known to \emph{not} be ℓ2-RIP with high probability.
With this backdrop, we show that there are no sparse matrices with ±1 entries that are ℓ2-RIP. On the other hand, for p≠2, we show that any ℓp-RIP matrix \emph{must} be sparse. Thus, sparsity is incompatible with ℓ2-RIP, but necessary for ℓp-RIP for p≠2.

Subjects: Computational Complexity (cs.CC); Information Theory (cs.IT)
Cite as: arXiv:2205.06738 [cs.CC]
  (or arXiv:2205.06738v1 [cs.CC] for this version)
  https://doi.org/10.48550/arXiv.2205.06738

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