8,989 research outputs found
CoCoA: A General Framework for Communication-Efficient Distributed Optimization
The scale of modern datasets necessitates the development of efficient
distributed optimization methods for machine learning. We present a
general-purpose framework for distributed computing environments, CoCoA, that
has an efficient communication scheme and is applicable to a wide variety of
problems in machine learning and signal processing. We extend the framework to
cover general non-strongly-convex regularizers, including L1-regularized
problems like lasso, sparse logistic regression, and elastic net
regularization, and show how earlier work can be derived as a special case. We
provide convergence guarantees for the class of convex regularized loss
minimization objectives, leveraging a novel approach in handling
non-strongly-convex regularizers and non-smooth loss functions. The resulting
framework has markedly improved performance over state-of-the-art methods, as
we illustrate with an extensive set of experiments on real distributed
datasets
Communication Efficient Distributed Optimization using an Approximate Newton-type Method
We present a novel Newton-type method for distributed optimization, which is
particularly well suited for stochastic optimization and learning problems. For
quadratic objectives, the method enjoys a linear rate of convergence which
provably \emph{improves} with the data size, requiring an essentially constant
number of iterations under reasonable assumptions. We provide theoretical and
empirical evidence of the advantages of our method compared to other
approaches, such as one-shot parameter averaging and ADMM
Regularized Decomposition of High-Dimensional Multistage Stochastic Programs with Markov Uncertainty
We develop a quadratic regularization approach for the solution of
high-dimensional multistage stochastic optimization problems characterized by a
potentially large number of time periods/stages (e.g. hundreds), a
high-dimensional resource state variable, and a Markov information process. The
resulting algorithms are shown to converge to an optimal policy after a finite
number of iterations under mild technical assumptions. Computational
experiments are conducted using the setting of optimizing energy storage over a
large transmission grid, which motivates both the spatial and temporal
dimensions of our problem. Our numerical results indicate that the proposed
methods exhibit significantly faster convergence than their classical
counterparts, with greater gains observed for higher-dimensional problems
L1-Regularized Distributed Optimization: A Communication-Efficient Primal-Dual Framework
Despite the importance of sparsity in many large-scale applications, there
are few methods for distributed optimization of sparsity-inducing objectives.
In this paper, we present a communication-efficient framework for
L1-regularized optimization in the distributed environment. By viewing
classical objectives in a more general primal-dual setting, we develop a new
class of methods that can be efficiently distributed and applied to common
sparsity-inducing models, such as Lasso, sparse logistic regression, and
elastic net-regularized problems. We provide theoretical convergence guarantees
for our framework, and demonstrate its efficiency and flexibility with a
thorough experimental comparison on Amazon EC2. Our proposed framework yields
speedups of up to 50x as compared to current state-of-the-art methods for
distributed L1-regularized optimization
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