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26 April 2024 |
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Article overview
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Seeing the Forest from the Trees in Two Looks: Matrix Sketching by Cascaded Bilateral Sampling | Kai Zhang
; Chuanren Liu
; Jie Zhang
; Hui Xiong
; Eric Xing
; Jieping Ye
; | Date: |
25 Jul 2016 | Abstract: | Matrix sketching is aimed at finding close approximations of a matrix by
factors of much smaller dimensions, which has important applications in
optimization and machine learning. Given a matrix A of size m by n,
state-of-the-art randomized algorithms take O(m * n) time and space to obtain
its low-rank decomposition. Although quite useful, the need to store or
manipulate the entire matrix makes it a computational bottleneck for truly
large and dense inputs. Can we sketch an m-by-n matrix in O(m + n) cost by
accessing only a small fraction of its rows and columns, without knowing
anything about the remaining data? In this paper, we propose the cascaded
bilateral sampling (CABS) framework to solve this problem. We start from
demonstrating how the approximation quality of bilateral matrix sketching
depends on the encoding powers of sampling. In particular, the sampled rows and
columns should correspond to the code-vectors in the ground truth
decompositions. Motivated by this analysis, we propose to first generate a
pilot-sketch using simple random sampling, and then pursue more advanced,
"follow-up" sampling on the pilot-sketch factors seeking maximal encoding
powers. In this cascading process, the rise of approximation quality is shown
to be lower-bounded by the improvement of encoding powers in the follow-up
sampling step, thus theoretically guarantees the algorithmic boosting property.
Computationally, our framework only takes linear time and space, and at the
same time its performance rivals the quality of state-of-the-art algorithms
consuming a quadratic amount of resources. Empirical evaluations on benchmark
data fully demonstrate the potential of our methods in large scale matrix
sketching and related areas. | Source: | arXiv, 1607.7395 | Services: | Forum | Review | PDF | Favorites |
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