1,458 research outputs found
Scalable Peaceman-Rachford Splitting Method with Proximal Terms
Along with developing of Peaceman-Rachford Splittling Method (PRSM), many
batch algorithms based on it have been studied very deeply. But almost no
algorithm focused on the performance of stochastic version of PRSM. In this
paper, we propose a new stochastic algorithm based on PRSM, prove its
convergence rate in ergodic sense, and test its performance on both artificial
and real data. We show that our proposed algorithm, Stochastic Scalable PRSM
(SS-PRSM), enjoys the convergence rate, which is the same as those
newest stochastic algorithms that based on ADMM but faster than general
Stochastic ADMM (which is ). Our algorithm also owns wide
flexibility, outperforms many state-of-the-art stochastic algorithms coming
from ADMM, and has low memory cost in large-scale splitting optimization
problems
The Free Cash Flow and Corporate Returns
Mcpherson (2018) and Jose, Lancaster, Stevens (1996) have written papers to examine the relationship between liquidity management and firm profitability. The literature establishes that the cash conversion cycle has an implication for the profitability and liquidity of a firm. We extend the time period and analyze the free cash flow instead of cash conversion cycle. We provide evidence that firms with higher free cash flows have higher risk adjusted stock returns
An Effective Combination of Different Order N-grams
In this paper an approach is proposed to combine different order N-grams based on the discriminative estimation criterion, on which the parameters of n-gram can be optimized. To raise the power of modeling language information, we propose several schemes to combine conventional different order n-gram language model. We employ Newton Gradient method to estimate the assumption probabilities and then test the optimally selected language model. We conduct experiments on the platform of conversion from Chinese pinyin to Chinese character. The experimental results show that the memory capacity of language model can be remarkably lowered with hide loss of accuracy. 1
Statistical Inference of Constrained Stochastic Optimization via Sketched Sequential Quadratic Programming
We consider statistical inference of equality-constrained stochastic
nonlinear optimization problems. We develop a fully online stochastic
sequential quadratic programming (StoSQP) method to solve the problems, which
can be regarded as applying Newton's method to the first-order optimality
conditions (i.e., the KKT conditions). Motivated by recent designs of numerical
second-order methods, we allow StoSQP to adaptively select any random stepsize
, as long as ,
for some control sequences and . To reduce the
dominant computational cost of second-order methods, we additionally allow
StoSQP to inexactly solve quadratic programs via efficient randomized iterative
solvers that utilize sketching techniques. Notably, we do not require the
approximation error to diminish as iteration proceeds. For the developed
method, we show that under mild assumptions (i) computationally, it can take at
most iterations (same as samples) to attain
-stationarity; (ii) statistically, its primal-dual sequence
converges to
a mean-zero Gaussian distribution with a nontrivial covariance matrix depending
on the underlying sketching distribution. Additionally, we establish the
almost-sure convergence rate of the iterate along with the
Berry-Esseen bound; the latter quantitatively measures the convergence rate of
the distribution function. We analyze a plug-in limiting covariance matrix
estimator, and demonstrate the performance of the method both on benchmark
nonlinear problems in CUTEst test set and on linearly/nonlinearly constrained
regression problems.Comment: 57 pages, 3 figures, 11 table
Land snails (Mollusca: Gastropoda) of India: status, threats and conservation strategies
Land snails form an important component in the forest ecosystem. In terms of number of species, the phylum Mollusca, to which land snails belong, is the largest phylum after Arthropoda. Mollusca provide unique ecosystem services including recycling of nutrients and they provide a prey base for small mammals, birds, snakes and other reptiles. However, land snails have the largest number of documented extinctions, compared to any other taxa. Till date 1,129 species of land snails are recorded from Indian territory. But only basic information is known about their taxonomy and little is known of their population biology, ecology and their conservation status. In this paper, we briefly review status, threats and conservation strategies of land snails of India
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