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تسجيل مستخدم جديدJointly Low-Rank and Bisparse Recovery: Questions and Partial Answers
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We investigate the problem of recovering jointly $r$-rank and $s$-bisparse matrices from as few linear measurements as possible, considering arbitrary measurements as well as rank-one measurements. In both cases, we show that $m asymp r s ln(en/s)$ measurements make the recovery possible in theory, meaning via a nonpractical algorithm. In case of arbitrary measurements, we investigate the possibility of achieving practical recovery via an iterative-hard-thresholding algorithm when $m asymp r s^gamma ln(en/s)$ for some exponent $gamma > 0$. We show that this is feasible for $gamma = 2$, and that the proposed analysis cannot cover the case $gamma leq 1$. The precise value of the optimal exponent $gamma in [1,2]$ is the object of a question, raised but unresolved in this paper, about head projections for the jointly low-rank and bisparse structure. Some related questions are partially answered in passing. For rank-one measurements, we suggest on arcane grounds an iterative-hard-thresholding algorithm modified to exploit the nonstandard restricted isometry property obeyed by this type of measurements.
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