Sharp Restricted Isometry Thresholds for Global Minima of Rank-Restricted Matrix LASSO
Abstract
We determine the sharp restricted isometry threshold for recovery at global minima of the rank-restricted matrix LASSO. For target rank r⋆, if the rank-k RIP constant satisfies δ<δsharp(k/r⋆), where δsharp(t)=t/(4−t) for 0<t<4/3 and δsharp(t)=√((t−1)/t) for t≥4/3, then every global minimizer has Frobenius error ≲√(r⋆)λ for all λ≳|𝒜*(ξ)|op and at every search rank r≥ r⋆. The constants depend only on the RIP constant and t=k/r⋆, and in particular are independent of the search rank. When the rank restriction is inactive, the result specializes to the ordinary convex matrix LASSO. We also obtain the analogous results for sparsity-restricted vector LASSO. Conversely, we show that the threshold δ<δsharp(k/r⋆) cannot be improved, due to the existence of counterexamples whose global minimizers fail to recover the ground truth.
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BibTeX
@misc{zhang2026sharp,
title = {{Sharp Restricted Isometry Thresholds for Global Minima of Rank-Restricted Matrix LASSO}},
author = {Richard Y. Zhang},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.29018},
eprint = {2608.29018},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.29018},
}
RIS
TY - UNPB
TI - Sharp Restricted Isometry Thresholds for Global Minima of Rank-Restricted Matrix LASSO
AU - Richard Y. Zhang
PY - 2026
DA - 2026/08/29
PB - arXiv
DO - 10.48550/arxiv.2608.29018
UR - https://arxiv.org/abs/2608.29018
AB - We determine the sharp restricted isometry threshold for recovery at global minima of the rank-restricted matrix LASSO. For target rank r_⋆, if the rank-k RIP constant satisfies δ<δ_sharp(k/r_⋆), where δ_sharp(t)=t/(4−t) for 0<t<4/3 and δ_sharp(t)=√((t−1)/t) for t≥4/3, then every global minimizer has Frobenius error ≲√(r_⋆)λ for all λ≳|𝒜^*(ξ)|_op and at every search rank r≥ r_⋆. The constants depend only on the RIP constant and t=k/r_⋆, and in particular are independent of the search rank. When the rank restriction is inactive, the result specializes to the ordinary convex matrix LASSO. We also obtain the analogous results for sparsity-restricted vector LASSO. Conversely, we show that the threshold δ<δ_sharp(k/r_⋆) cannot be improved, due to the existence of counterexamples whose global minimizers fail to recover the ground truth.
ER -