Research
On-device research index

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.

168,878 papers · 148 categories

Trend · papers per month

2356 · Jun 202019922001200920172026
48 results for matrix-variate t-distributions

A parsimonious model reduces over-parameterization in skewed matrix variate mixtures.

problem Over-parameterization in skewed matrix variate mixtures.
method Parsimonious family of 256 models using bilinear factor analyzers constrained over clusters, with AECM algorithm for estimation.
result Extensive simulations and real-world datasets (MNIST, Olivetti faces) demonstrate the method's effectiveness.

In recent years, data have become increasingly higher dimensional and, therefore, an increased need has arisen for dimension reduction techniques for clustering. Although such techniques are firmly established in the literature for multivariate data, there is a relative paucity in the area of matrix variate, or three-w…

2018-09-07abs ↗pdf ↗

Over the years data has become increasingly higher dimensional, which has prompted an increased need for dimension reduction techniques. This is perhaps especially true for clustering (unsupervised classification) as well as semi-supervised and supervised classification. Although dimension reduction in the area of clus…

2017-12-22abs ↗pdf ↗

Undirected graphs can be used to describe matrix variate distributions. In this paper, we develop new methods for estimating the graphical structures and underlying parameters, namely, the row and column covariance and inverse covariance matrices from the matrix variate data. Under sparsity conditions, we show that one…

2012-09-23abs ↗pdf ↗

A distributed framework for reducing high-dimensional matrix-variate time series data.

problem Reducing dimensionality of high-dimensional, heterogeneous matrix-variate time series data.
method Data partitioning, distributed two-dimensional tensor PCA, aggregation, final PCA, factor matrix computation.
result Preserves latent matrix structure, improves computational efficiency and information utilization.

Estimates covariance matrices for matrix-variate data via core covariance geometry.

problem Estimating covariance matrices for matrix-variate data with partial isotropy.
method Fixed-rank core covariance geometry, partial-isotropy rank-r core shrinkage estimator.
result The geometry of the space of rank-r cores is a smooth manifold.

Variational Bayesian neural networks combine the flexibility of deep learning with Bayesian uncertainty estimation. However, inference procedures for flexible variational posteriors are computationally expensive. A recently proposed method, noisy natural gradient, is a surprisingly simple method to fit expressive poste…

2018-11-30abs ↗pdf ↗

This paper proposes robust matrix variate regression models with rank constraints and vector regularization.

problem High dimensional and noisy matrix-valued predictors in regression models.
method Rank constraint, vector regularization, alternating projected gradient descent algorithm.
result The proposed method achieves the minimax rate of estimation errors.

Transposable data represents interactions among two sets of entities, and are typically represented as a matrix containing the known interaction values. Additional side information may consist of feature vectors specific to entities corresponding to the rows and/or columns of such a matrix. Further information may also…

2014-04-27abs ↗pdf ↗

The paper derives formulas for moments of a Student t distribution and applies them to quantify LpL_p-quantiles.

problem Understanding the moments and quantiles of a Student t distribution.
method Developed formulas for partial and complete moments, and derived relationships between LpL_p-quantiles.
result For a Student t distribution, the Lnj+1L_{n-j+1}-quantile and LjL_j-quantile coincide at any confidence level.

Cluster GARCH model improves multivariate GARCH for high-dimensional asset returns.

problem Modeling high-dimensional asset returns with flexible tail dependencies and cluster structures.
method Introduced a novel multivariate GARCH model with flexible convolution-t distributions, tractable likelihood and derivatives for dynamic correlation structure.
result Cluster GARCH model outperforms existing models in daily returns of 100 assets, both in-sample and out-of-sample.

TDistNNs improve prediction intervals for neural networks by using t-distributions.

problem Traditional neural networks provide only point estimates, lacking predictive uncertainty.
method TDistNNs generate t-distributed outputs with adjustable degrees of freedom, enhancing robustness to non-Gaussian data.
result TDistNNs produce narrower prediction intervals with proper coverage compared to Gaussian-based PNNs.

Modified Jones-Faddy skew t-distribution captures asymmetry in stock returns.

problem Negative skew and positive mean in stock returns due to broken symmetry of stochastic volatility.
method Modified Jones-Faddy skew t-distribution applied to split gains and losses, using stochastic differential equations for stock returns and volatility.
result The modified distribution effectively captures the asymmetry in daily S&P500 returns, including its tails.

Generative Adversarial Networks (GANs) have a great performance in image generation, but they need a large scale of data to train the entire framework, and often result in nonsensical results. We propose a new method referring to conditional GAN, which equipments the latent noise with mixture of Student's t-distributio…

2018-11-06abs ↗pdf ↗

Analyzes multi-day stock returns, showing linear volatility and mean dependence.

problem Linear dependence of volatility and mean in accumulated stock returns.
method Modified Jones-Faddy skew t-distribution analysis.
result Linear dependence of volatility and mean on the number of days of accumulation.

Optimal option portfolios under Sharpe Ratio maximization with skew-elliptical t-distributed returns

problem Optimal option portfolios under Sharpe Ratio maximization
method Formulation for explicit portfolio weights
result Different optimal portfolios for Sharpe Ratio and return-to-Value-at-Risk (VaR) ratio

A new operator based on t-distributions improves NN classifiers' robustness to out-of-distribution samples.

problem NN classifiers assign extreme probabilities to out-of-distribution samples, leading to unreliable predictions.
method Derive a novel operator using t-distributions to model uncertainty more accurately.
result Classifiers using the new operator are more robust to out-of-distribution samples.

Cluster analysis is a fundamental tool for pattern discovery of complex heterogeneous data. Prevalent clustering methods mainly focus on vector or matrix-variate data and are not applicable to general-order tensors, which arise frequently in modern scientific and business applications. Moreover, there is a gap between …

2018-03-17abs ↗pdf ↗

Adaptive t-distribution estimates nonstationary time series using moving moments.

problem Nonstationary time series with varying dependence structure.
method Moving estimator optimizing a weighted log-likelihood, using exponential moving averages for moments.
result Evolution of ν parameter in Student's t-distribution, capturing tail behavior and extreme events.

MMM model clusters mixed-type longitudinal data efficiently.

problem Challenges in clustering multivariate longitudinal mixed-type data.
method MMM model reorganizes data into a three-way structure, using a mixture of matrix-variate normal distributions.
result MMM model handles various data types (continuous, ordinal, binary, nominal, count) and temporal dependence.

Differential privacy mechanism design has traditionally been tailored for a scalar-valued query function. Although many mechanisms such as the Laplace and Gaussian mechanisms can be extended to a matrix-valued query function by adding i.i.d. noise to each element of the matrix, this method is often suboptimal as it for…

2018-01-02abs ↗pdf ↗

A new filter adapts to heavy-tailed data without tuning, improving performance in challenging conditions.

problem Degraded performance of Kalman and EnKF in heavy-tailed distributions.
method Generalizes EnKF using t-distributions, estimating parameters via EM algorithm.
result Improves performance on challenging filtering problems with heavy-tailed noise.

Graphical Gaussian models have proven to be useful tools for exploring network structures based on multivariate data. Applications to studies of gene expression have generated substantial interest in these models, and resulting recent progress includes the development of fitting methodology involving penalization of th…

2014-08-09abs ↗pdf ↗

The probability distribution of log-returns of financial time series, sampled at high frequency, is the basis for any further developments in quantitative finance. In this letter, we present experimental results based on a large set of time series on futures. Then, we show that the t-distribution with ν3ν\simeq 3 gives…

2011-10-05abs ↗pdf ↗

Paper studies t-SNE convergence with generalized kernels.

problem Understanding convergence of t-SNE with generalized kernels.
method Concrete formulation of generalized kernels, proving convergence to an equilibrium distribution.
result t-SNE converges to an equilibrium distribution under certain conditions for generalized kernels.

Study connects covariance cleaning theory to information theory for heavy-tailed distributions.

problem Optimizing covariance matrices for heavy-tailed distributions using information theory.
method Minimizing Frobenius norm and information loss between true and estimated covariance matrices.
result Asymptotic regime of large matrices minimizes information loss for Student's t distributions.

Improved VAE for heavy-tailed data using Student's t-distributions.

problem Over-regularization in VAEs with Gaussian priors.
method Proposed t3t^3VAE framework with Student's t-distributions for prior, encoder, and decoder.
result Significantly outperforms other models on heavy-tailed datasets.

We propose a robust method to estimate heteroscedastic noise models using Student's t-distribution.

problem Identifying cause and effect from bivariate observational data with non-Gaussian noise.
method We propose a novel approach using Student's t-distribution to estimate heteroscedastic noise models, which is more robust and achieves better performance.
result Our estimators are more robust and achieve better overall performance across synthetic and real benchmarks.

New diffusion models capture heavy-tailed distributions better.

problem Diffusion models struggle with rare or extreme events in heavy-tailed distributions.
method Repurposed diffusion framework using multivariate Student-t distributions, tailored perturbation kernel, and γγ-divergence.
result Our models generate rare and extreme events more effectively than standard diffusion models.