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arXiv research

A locally-built, LLM-digested index of recent arXiv papers in quant finance, geometry/topology, and statistical ML — keyword search served straight from SQLite on this machine.

168,932 papers · 148 categories

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48 results for natural algorithms

We introduce a simple algorithm, True Asymptotic Natural Gradient Optimization (TANGO), that converges to a true natural gradient descent in the limit of small learning rates, without explicit Fisher matrix estimation. For quadratic models the algorithm is also an instance of averaged stochastic gradient, where the par…

2017-12-22abs ↗pdf ↗

The paper characterizes conditions for convergence of RL methods with linear approximations.

problem Characterizing non-uniqueness issues for reinforcement learning algorithms with linear function approximation.
method Proves a condition on features that determines convergence or non-uniqueness of natural algorithms.
result Natural algorithms converge to the correct solution if and only if value functions in the approximation space satisfy a certain shape.

Proposes model-based robust deep learning to handle natural variation in data.

problem Deep learning's fragility to natural variation in data.
method Develops model-based robust training algorithms using deep generative models to learn natural variation.
result Deep neural networks trained with model-based algorithms outperform standard and norm-bounded robust algorithms.

A quantum reinforcement learning algorithm reduces sample complexity.

problem Quantum reinforcement learning under model-free settings with quantum oracle access.
method Quantum Natural Policy Gradient (QNPG) algorithm replacing random sampling with deterministic gradient estimation.
result QNPG achieves a sample complexity of ildeO(ε1.5) ilde{\mathcal{O}}(ε^{-1.5}) for queries to the quantum oracle, significantly improving classical lower bound.

Two novel distributed VB algorithms improve Bayesian inference in sensor networks.

problem Efficient inference in Bayesian frameworks for sensor networks.
method Two novel distributed VB algorithms for general Bayesian inference, using stochastic natural gradient and ADMM.
result Distributed algorithms perform nearly as well as centralized ones, demonstrating excellent performance.

We propose a solution to the image deconvolution problem where the convolution kernel or point spread function (PSF) is assumed to be only partially known. Small perturbations generated from the model are exploited to produce a few principal components explaining the PSF uncertainty in a high dimensional space. Unlike …

2012-03-21abs ↗pdf ↗

NVA combines variational posteriors, annealing, and natural-gradient learning for multimodal optimization.

problem Finding multiple global and local modes in nonconvex objectives.
method NVA integrates variational posteriors, annealing, and natural-gradient learning.
result NVA outperforms gradient descent and evolution strategies on simulations and real-world problems.

The paper proposes a method to train time-varying generative models using natural gradients.

problem Training time-varying generative models efficiently and accurately.
method Projecting generative model parameters onto an exponential family manifold and optimizing using natural gradient descent.
result The proposed method efficiently approximates the natural gradient and can be applied to various exponential family models.

We present a novel algorithm to train a deep Q-learning agent using natural-gradient techniques. We compare the original deep Q-network (DQN) algorithm to its natural-gradient counterpart, which we refer to as NGDQN, on a collection of classic control domains. Without employing target networks, NGDQN significantly outp…

2018-03-20abs ↗pdf ↗

The goal of reinforcement learning algorithms is to estimate and/or optimise the value function. However, unlike supervised learning, no teacher or oracle is available to provide the true value function. Instead, the majority of reinforcement learning algorithms estimate and/or optimise a proxy for the value function. …

2018-05-24abs ↗pdf ↗

We introduce Natural Neural Networks, a novel family of algorithms that speed up convergence by adapting their internal representation during training to improve conditioning of the Fisher matrix. In particular, we show a specific example that employs a simple and efficient reparametrization of the neural network weigh…

2015-07-01abs ↗pdf ↗

Paper provides convergence guarantees for off-policy NAC with finite sample complexity.

problem Convergence analysis of off-policy natural actor-critic algorithm.
method Finite-sample analysis with Importance Sampling and Q-trace algorithm.
result Converges to global optimal policy with sample complexity O(ε3log2(1/ε))\mathcal{O}(ε^{-3}\log^2(1/ε)).

New framework improves EM algorithm convergence under log-Sobolev inequality.

problem Improving convergence of the EM algorithm.
method Extending gradient flow techniques to EM algorithm, using free energy representation.
result Exponential convergence of EM algorithm under log-Sobolev inequality.

Fair HAC algorithms ensure clustering fairness across protected groups.

problem Ensuring clustering fairness in HAC algorithms when datasets contain biases.
method Proposes fair algorithms for HAC that enforce fairness constraints regardless of distance linkage criteria.
result Our fair HAC algorithms find fairer clusterings compared to vanilla HAC and other fair clustering approaches.

The ability to characterize the color content of natural imagery is an important application of image processing. The pixel by pixel coloring of images may be viewed naturally as points in color space, and the inherent structure and distribution of these points affords a quantization, through clustering, of the color i…

2012-02-20abs ↗pdf ↗

Improved Bayesian learning rule handles positive-definite constraints efficiently.

problem Bayesian learning rule struggles with positive-definite constraints.
method Proposes an improved rule using Riemannian gradient methods for block-coordinate natural parameterization.
result Outperforms existing methods without increased computation.

An algorithm was recently introduced by INTECH for the purposes of estimating the trading-profit contribution of systematic rebalancing to the relative return of rules-based investment strategies. We apply this methodology to analyze the size factor through the use of equal-weighted portfolios. These strategies combine…

2016-01-28abs ↗pdf ↗

A new optimization algorithm for Gaussian Variational Inference on precision matrices.

problem Complex models with positive definite constraints on covariance matrices.
method Manifold Gaussian Variational Bayes (MGVBP) with natural gradient updates.
result Empirically validated as a feasible and efficient solution for VI in complex models.

Square-root natural-gradient improves variational inference convergence.

problem Challenges in establishing theoretical convergence guarantees for natural-gradient descent.
method Square-root parameterization for Gaussian covariance.
result Establishes novel convergence guarantees for natural-gradient Gaussian inference.

Proposes an alternative method to train RBMs with binary synapses using Bayesian learning rule.

problem Training RBMs with binary synapses is challenging due to discrete nature of synapses.
method Proposes an alternative optimization method using the Bayesian learning rule, updating natural parameters instead of expectation parameters.
result No additional clipping is needed as natural parameters take values in the entire real domain.

The paper defines conditions for learning causal graphs from data with unobserved variables.

problem Learning causal graphs from data with unobserved variables.
method Formalizes constraint-based structure learning algorithms under conditions and assumptions.
result Natural family of algorithms output Markov equivalent graphs to the causal graph under faithfulness assumption.

New algorithm reduces complexity in multi-agent reinforcement learning.

problem High computational complexity in exact computations for multi-agent reinforcement learning.
method Design of a scalable algorithm based on Natural Policy Gradient, using local information and limited communication.
result Converges to globally optimal policy with dimension-free complexity and localization error.

This paper presents Natural Evolution Strategies (NES), a recent family of algorithms that constitute a more principled approach to black-box optimization than established evolutionary algorithms. NES maintains a parameterized distribution on the set of solution candidates, and the natural gradient is used to update th…

2011-06-22abs ↗pdf ↗

New algorithm for risk-sensitive reinforcement learning with natural policy gradients.

problem Risk-sensitive reinforcement learning with downside risk constraints.
method Introduce a new Bellman equation to estimate the lower partial moment of returns, use natural policy gradients, and extend Reward Constrained Policy Optimization.
result Sample-efficient estimation of partial moments and effective risk-sensitive control.

Much work has been done refining and characterizing the receptive fields learned by deep learning algorithms. A lot of this work has focused on the development of Gabor-like filters learned when enforcing sparsity constraints on a natural image dataset. Little work however has investigated how these filters might expan…

2012-10-31abs ↗pdf ↗

Entropy-regularized NPG methods converge linearly in discounted MDPs.

problem Theoretical limitations of NPG methods in reinforcement learning.
method Entropy regularization in conjunction with NPG methods for discounted MDPs.
result Entropy-regularized NPG methods converge linearly in discounted MDPs.

This paper introduces the Metric-Free Natural Gradient (MFNG) algorithm for training Boltzmann Machines. Similar in spirit to the Hessian-Free method of Martens [8], our algorithm belongs to the family of truncated Newton methods and exploits an efficient matrix-vector product to avoid explicitely storing the natural g…

2013-01-16abs ↗pdf ↗

A new test improves statistical inference in bandit algorithms without sacrificing adaptiveness.

problem Challenges in statistical inference for adaptive randomised experiments in bandits.
method An allocation probability test for Thompson Sampling without trading-off regret or requiring large sample sizes.
result Improves statistical inference in small samples, showing advantages in mental health experiments.