120,158 research outputs found
Matrix Recipes for Hard Thresholding Methods
In this paper, we present and analyze a new set of low-rank recovery
algorithms for linear inverse problems within the class of hard thresholding
methods. We provide strategies on how to set up these algorithms via basic
ingredients for different configurations to achieve complexity vs. accuracy
tradeoffs. Moreover, we study acceleration schemes via memory-based techniques
and randomized, -approximate matrix projections to decrease the
computational costs in the recovery process. For most of the configurations, we
present theoretical analysis that guarantees convergence under mild problem
conditions. Simulation results demonstrate notable performance improvements as
compared to state-of-the-art algorithms both in terms of reconstruction
accuracy and computational complexity.Comment: 26 page
Global Thresholding and Multiple Pass Parsing
We present a variation on classic beam thresholding techniques that is up to
an order of magnitude faster than the traditional method, at the same
performance level. We also present a new thresholding technique, global
thresholding, which, combined with the new beam thresholding, gives an
additional factor of two improvement, and a novel technique, multiple pass
parsing, that can be combined with the others to yield yet another 50%
improvement. We use a new search algorithm to simultaneously optimize the
thresholding parameters of the various algorithms.Comment: Fixed latex errors; fixed minor errors in published versio
Two-Sample Tests for High Dimensional Means with Thresholding and Data Transformation
We consider testing for two-sample means of high dimensional populations by
thresholding. Two tests are investigated, which are designed for better power
performance when the two population mean vectors differ only in sparsely
populated coordinates. The first test is constructed by carrying out
thresholding to remove the non-signal bearing dimensions. The second test
combines data transformation via the precision matrix with the thresholding.
The benefits of the thresholding and the data transformations are showed by a
reduced variance of the test thresholding statistics, the improved power and a
wider detection region of the tests. Simulation experiments and an empirical
study are performed to confirm the theoretical findings and to demonstrate the
practical implementations.Comment: 64 page
Exact Hybrid Covariance Thresholding for Joint Graphical Lasso
This paper considers the problem of estimating multiple related Gaussian
graphical models from a -dimensional dataset consisting of different
classes. Our work is based upon the formulation of this problem as group
graphical lasso. This paper proposes a novel hybrid covariance thresholding
algorithm that can effectively identify zero entries in the precision matrices
and split a large joint graphical lasso problem into small subproblems. Our
hybrid covariance thresholding method is superior to existing uniform
thresholding methods in that our method can split the precision matrix of each
individual class using different partition schemes and thus split group
graphical lasso into much smaller subproblems, each of which can be solved very
fast. In addition, this paper establishes necessary and sufficient conditions
for our hybrid covariance thresholding algorithm. The superior performance of
our thresholding method is thoroughly analyzed and illustrated by a few
experiments on simulated data and real gene expression data
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