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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.

169,051 papers · 148 categories

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48 results for covariance based superpixels

Paper presents a graph-based semi-supervised method for hyperspectral image classification.

problem Hyperspectral image classification with limited labeled data.
method Novel superpixel algorithm based on spectral covariance matrix, followed by superpixel graph construction and classification.
result The method outperforms state-of-the-art approaches, especially in scenarios with minimal labeled data.

Study compares different superpixel methods for explaining CNNs in biological images.

problem Transparency of deep learning models in image classification.
method Compared Felzenszwalb, SLIC, and Compact-Watershed superpixel methods on explaining CNNs.
result Compact-Watershed method most closely matches human-referenced relevance areas.

Novel graph-based framework for hyperspectral image classification using superpixels.

problem High classification accuracy with limited labelled data in hyperspectral images.
method Superpixel method for defining local regions, spectral and spatial features extraction, contracted graph representation, semi-supervised classifier.
result Our approach produces accurate classifications with minimal labelled data, outperforming state-of-the-art techniques.

ViCE uses superpixels to enhance self-supervised learning for better dense visual embeddings.

problem Lack of high-resolution feature maps from self-supervised models.
method Superpixels for dense representation learning, contrasting over regions.
result Improves unsupervised semantic segmentation on benchmarks like Cityscapes and COCO.

Gradient Weighted Superpixels improve CNN interpretability without sacrificing speed.

problem Efficiency vs. interpretability trade-off in CNNs, especially for large input volumes.
method Gradient-based pixel scoring techniques applied to superpixels.
result Superpixels approximate LIME in a fraction of the time, improving interpretability.

This research adapts superpixels for Shapley value computation in DNA profile classification.

problem Efficiently computing Shapley values for large, multidimensional time-series data.
method Adapting the concept of superpixels to streamline Shapley value computation for time-series-like data.
result Realistic, accurate, and fast computation of Shapley values for DNA profile classification.

SLIC-UAV monitors forest recovery using UAVs and machine learning.

problem Challenges in monitoring forest recovery, especially in logged tropical forests.
method Novel pipeline for UAV imagery analysis, combining crown labelling, species classification, and superpixel segmentation.
result SLIC-UAV achieves high accuracy in species mapping, from 79.3% to 90.5%.

The paper simplifies quickshift hyperparameter tuning for larger images.

problem Understanding and tuning hyperparameters for quickshift image segmentation.
method Theoretical analysis of a modified quickshift algorithm for homogeneous patches with i.i.d. noise.
result A heuristic to scale quickshift hyperparameters based on image size.

This paper presents a new probabilistic generative model for image segmentation, i.e. the task of partitioning an image into homogeneous regions. Our model is grounded on a mid-level image representation, called a region tree, in which regions are recursively split into subregions until superpixels are reached. Given t…

2015-06-11abs ↗pdf ↗

Novel approach for SEM in small samples with p>np>n.

problem Small sample size and p>np>n issues in factor-based SEM.
method Reformulates covariance structure into self-covariance and cross-covariance, defines a feasible set with relative error constraint.
result Improved stability and directional information in small-sample settings.

Enhanced Transformer models predict ETF portfolio performance by optimizing covariance and semi-covariance matrices.

problem Static covariance estimates fail to capture dynamic market fluctuations and non-linear correlations.
method Transformer-based models for real-time covariance and semi-covariance predictions.
result Portfolios optimized with semi-covariance matrix outperform those with standard covariance matrix, especially in volatile conditions.

Scene parsing is an important and challenging prob- lem in computer vision. It requires labeling each pixel in an image with the category it belongs to. Tradition- ally, it has been approached with hand-engineered features from color information in images. Recently convolutional neural networks (CNNs), which automatica…

2014-11-15abs ↗pdf ↗

A new GNN architecture called coVariance neural network (VNN) improves stability and transferability of covariance matrix analysis.

problem Stability and transferability issues in covariance matrix analysis.
method Developed coVariance neural network (VNN) that operates on sample covariance matrices.
result VNN is more stable and transferable than PCA-based approaches.

A new covariance estimator reduces dimensionality and improves portfolio forecasting.

problem Estimating high-dimensional covariance matrices with weak factors.
method Sparse Approximate Factor (SAF) model with l1l_1-regularization.
result SAF estimator outperforms other methods in portfolio forecasting.

New non-separable covariance kernels for spatiotemporal data derived from harmonic oscillator physics.

problem Capturing complex spatiotemporal dependencies in Gaussian processes.
method Hybrid spectral method based on the harmonic oscillator, deriving explicit covariance kernels.
result Explicit non-separable covariance kernels with space-time interactions.

Many machine learning algorithms require precise estimates of covariance matrices. The sample covariance matrix performs poorly in high-dimensional settings, which has stimulated the development of alternative methods, the majority based on factor models and shrinkage. Recent work of Ledoit and Wolf has extended the sh…

2016-11-02abs ↗pdf ↗

Paper proposes DP-Thresholding for estimating sparse high-dimensional covariance matrices with differential privacy.

problem Estimating sparse high-dimensional covariance matrices under differential privacy constraints.
method DP-Thresholding method for achieving non-trivial error bounds.
result DP-Thresholding achieves significant error bounds compared to existing methods.

Improved covariate shift handling with node-based Bayesian neural networks.

problem Improving generalization under covariate shift in neural networks.
method Introduced node-based Bayesian neural networks that learn latent noise variables to represent input corruptions.
result Node-based BNNs perform well under covariate shift due to input perturbations, improving uncertainty estimation and robustness.

The paper analyzes how Gaussian kernel parameters affect posterior covariance in Gaussian processes.

problem Understanding the influence of Gaussian kernel parameters on posterior covariance in Gaussian processes.
method Geometric analysis and a posteriori error estimation techniques from adaptive finite element methods.
result The bandwidth parameter and spatial distribution of observations significantly influence posterior covariance and its matrix.

optHSIC tests independence between covariates and censored lifetimes using optimal transport.

problem Testing independence between a covariate and right-censored lifetimes.
method optHSIC uses optimal transport to transform censored data into uncensored data, then applies a permutation test with a kernel-based dependence measure.
result optHSIC has power against a wider class of alternatives than Cox regression and maintains type 1 error control even when censoring depends on the covariate.

A new model DKMPP integrates covariates and uses an integration-free method for spatio-temporal point processes.

problem Training intractable deep spatio-temporal point processes with multimodal covariates.
method DKMPP uses a deep kernel to model complex relationships and an integration-free score matching method.
result DKMPP and score-based estimators outperform baseline models in spatio-temporal point processes.

Develops a new MCMC-based Wishart prior for Gaussian Process covariance matrix.

problem Difficult inference for multivariate Gaussian Processes with multiple lengthscale parameters.
method Introduces a self-assembled Wishart prior and uses MCMC for Bayesian inference on kernel hyperparameters.
result Demonstrates the effectiveness of the new prior in GP-based learning with empirical results.

Optimally tackles covariate shift in RKHS-based nonparametric regression.

problem Covariate shift in nonparametric regression over RKHS.
method Two families of covariate shift problems defined using likelihood ratios. Minimax rate-optimal estimators for KRR and reweighted KRR.
result KRR is minimax rate-optimal and strictly sub-optimal compared to naive estimator under covariate shift.

A scalable algorithm for GP regression selects relevant covariates efficiently.

problem Scalable variable selection in large GP regression models.
method VGPR algorithm using Vecchia approximation for sparse precision matrix, mini-batch subsampling.
result Improved scalability and accuracy in selecting relevant covariates.

Compact bilinear pooling approximates covariance features for faster training.

problem Efficiently approximating covariance features for faster training.
method Compact bilinear pooling extended to polynomial approximations of covariance features.
result The proposed method achieves comparable accuracy with fewer dimensions.

Paper develops efficient mechanisms for estimating variance and covariance under differential privacy in the add-remove model.

problem Estimating variance and covariance under differential privacy in the add-remove model.
method Developed mechanisms based on the Bézier mechanism, a novel moment-release framework.
result Proved minimax optimality of the Bézier-based estimator in the high-privacy regime and demonstrated its better utility in instance-wise analysis.

TraCeR uses transformers to analyze survival data with longitudinal covariates.

problem Handling longitudinal covariates and assessing model calibration in survival analysis.
method Transformer-based survival analysis framework with factorized self-attention architecture.
result TraCeR achieves significant performance improvements over state-of-the-art methods.

Study nonparametric covariance function estimation for noisy data.

problem Estimating covariance function from discrete noisy data in high dimensions.
method Adaptive learning-based estimators, including deep learning.
result Established oracle inequality and convergence rates for deep learning estimators.

SPARKLE handles high-dimensional covariates for online decision-making.

problem Complex reward-covariate relationships in high-dimensional settings.
method SPARKLE uses a sparse additive reward model with doubly penalized estimator and adaptive screening.
result SPARKLE achieves sublinear regret bound logarithmic in covariate dimensionality.