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There has been significant recent work on the theory and application of randomized coordinate descent algorithms, beginning with the work of Nesterov [SIAM J. Optim., 22(2), 2012 ], who showed that a random-coordinate selection rule achieves the same convergence rate as the Gauss-Southwell selection rule. This result suggests that we should never use the(More)
This paper presents a new perceptual image hashing approach that exploits the image color information using hypercomplex (quaternionic) representations. Unlike grayscale-based techniques, the proposed approach preserves the color interaction between the image components that have a significant contribution in the generated perceptual image hash codes.(More)
The Kaczmarz method is an iterative algorithm for solving systems of linear equalities and inequalities , that iteratively projects onto these constraints. Recently, Strohmer and Vershynin [J. gave a non-asymptotic convergence rate analysis for this algorithm, spurring numerous extensions and generalizations of the Kaczmarz method. Rather than the(More)
In this document, we derive several results and present additional experiments that were omitted from the main paper due to space limitations. To allow easy referencing, the sections are numbered according to the location in the main paper that they are referenced. We first give additional details on how to calculate the GS rule efficiently for sparse(More)
We consider solving linear systems with Kaczmarz methods. Strohmer & Vershynin [2009] show linear convergence with randomized row selection. Does it make sense to use greedy row selection? Our contributions: Efficient implementation of greedy rules for sparse A. Faster convergence rates for greedy selection rules. Analysis of approximate greedy selection(More)
Unlike text files, XML-based documents have structure as a property that facilitates their categorization to their respective classes. Therefore, it is imperative to have structure as an integral part of the feature vector representing an XML document. To date, many models incorporating structural information were proposed. Structure Link Vector Model(More)
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