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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.

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48 results for sketching methods

The paper sharpens the analysis of sketch-and-project methods using randomized singular value decomposition.

problem Improving convergence rates of sketch-and-project methods for solving linear systems and non-linear optimization problems.
method Developing a theoretical framework and new spectral bounds for the expected sketched projection matrix.
result The convergence rate improves linearly with sketch size and even faster with certain spectral decays.

A new method for estimating large-scale linear models with improved precision.

problem Estimating large-scale linear statistical models efficiently.
method Sequential Least-Squares Estimators with Fast Randomized Sketching (SLSE-FRS), integrating Sketch-and-Solve and Iterative-Sketching methods.
result SLSE-FRS produces high-precision estimators, outperforming state-of-the-art methods.

New method reduces linear regret in high-dimensional bandit problems.

problem Heavy spectral tails in streaming matrices lead to linear regret in sketch-based linear bandits.
method Dyadic Block Sketching, a multi-scale matrix sketching approach.
result Achieves sublinear regret bounds without prior knowledge of streaming matrix properties.

We introduce a new sub-linear space sketch---the Weight-Median Sketch---for learning compressed linear classifiers over data streams while supporting the efficient recovery of large-magnitude weights in the model. This enables memory-limited execution of several statistical analyses over streams, including online featu…

2017-11-07abs ↗pdf ↗

Iterative Hessian sketch (IHS) is an effective sketching method for modeling large-scale data. It was originally proposed by Pilanci and Wainwright (2016; JMLR) based on randomized sketching matrices. However, it is computationally intensive due to the iterative sketch process. In this paper, we analyze the IHS algorit…

2019-02-20abs ↗pdf ↗

We present sketch-rnn, a recurrent neural network (RNN) able to construct stroke-based drawings of common objects. The model is trained on thousands of crude human-drawn images representing hundreds of classes. We outline a framework for conditional and unconditional sketch generation, and describe new robust training …

2017-04-11abs ↗pdf ↗

Sketch-BERT learns vector sketches using BERT-like self-supervised learning.

problem Lack of effective vector sketch representation for recognition and retrieval tasks.
method Generalized BERT to sketch domain with novel embedding networks and self-supervised sketch gestalt learning.
result Improved performance on sketch recognition, retrieval, and gestalt tasks.

We accelerate the power method for strong low-rank approximation using fast sketching.

problem Efficiency bottleneck in power method for large target ranks.
method Developed an algorithmic and theoretical framework for accelerating the power method using fast sketching.
result Simple and provably efficient methods for singular value decomposition, low-rank factorization, and Nyström approximation.

Sketch-GNN reduces GNN training time and memory usage to sublinear scales.

problem Training GNNs on large graphs is computationally expensive and memory-intensive.
method Develops a sketch-based algorithm that trains GNNs on compact sketches of graph adjacency and node embeddings.
result Training time and memory usage grow sublinearly with respect to graph size.

Large-scale distributed training of neural networks is often limited by network bandwidth, wherein the communication time overwhelms the local computation time. Motivated by the success of sketching methods in sub-linear/streaming algorithms, we introduce Sketched SGD, an algorithm for carrying out distributed SGD by c…

2019-03-12abs ↗pdf ↗

A parallel optimization method for convex functions using Hessian sketching and debiasing.

problem Massively parallel optimization of convex functions with limited communication.
method Newton method with Hessian sketching and debiasing by workers, server averages descent directions.
result Approximation of Newton step with low-complexity adaptive sketching scheme.

One-pass private sketch supports various machine learning tasks.

problem Efficiently supporting multiple machine learning tasks with differential privacy.
method Randomized contingency tables indexed with locality-sensitive hashing, constructed in one pass.
result Competitive error bounds for DP kernel density estimation, faster than existing methods.

Tensor CANDECOMP/PARAFAC (CP) decomposition has wide applications in statistical learning of latent variable models and in data mining. In this paper, we propose fast and randomized tensor CP decomposition algorithms based on sketching. We build on the idea of count sketches, but introduce many novel ideas which are un…

2015-06-14abs ↗pdf ↗

A new method reduces the complexity of tensor products from cubic to quadratic, improving both speed and accuracy.

problem Efficiently computing high-dimensional tensor products for polynomial kernels.
method Complex-to-Real (CtR) modification of sketches using complex random projections.
result Achieves state-of-the-art performance in accuracy and speed.

Develops precise expressions for random projections for better machine learning tasks.

problem Improving the accuracy of dimensionality reduction in machine learning tasks.
method Exploits recent developments in spectral analysis of random matrices to derive accurate expressions for random projection matrices.
result Provides precise expressions that reflect the practical performance of sketching methods, including Gaussian and Rademacher sketches.

The paper develops methods to estimate frequencies in large discrete data sets with improved coverage and robustness.

problem Estimating frequencies in large, discrete data sets with valid coverage and robustness.
method Conformal inference methods using discrete sketches, marginal coverage for queries, and novel conformal calibration.
result Improved empirical performance compared to existing methods in simulations and real data.

We present a mechanism to compute a sketch (succinct summary) of how a complex modular deep network processes its inputs. The sketch summarizes essential information about the inputs and outputs of the network and can be used to quickly identify key components and summary statistics of the inputs. Furthermore, the sket…

2019-05-29abs ↗pdf ↗

New algorithm converts data into sub-gaussian designs efficiently.

problem Efficiently converting large datasets into sub-gaussian random designs for robust performance.
method Algorithmic Gaussianization through sketching and averaging, using LESS embeddings.
result Efficient data sketches nearly indistinguishable from sub-gaussian designs.

We present a probabilistic model for Sketch-Based Image Retrieval (SBIR) where, at retrieval time, we are given sketches from novel classes, that were not present at training time. Existing SBIR methods, most of which rely on learning class-wise correspondences between sketches and images, typically work well only for …

2019-04-18abs ↗pdf ↗

We show that a simple randomized sketch of the matrix multiplicative weight (MMW) update enjoys (in expectation) the same regret bounds as MMW, up to a small constant factor. Unlike MMW, where every step requires full matrix exponentiation, our steps require only a single product of the form eAbe^A b, which the Lanczos …

2019-03-07abs ↗pdf ↗

Localized sketching improves matrix multiplication and ridge regression complexity.

problem Efficiently approximate matrix multiplication and ridge regression with limited data availability.
method Localized sketching matrices for block diagonal structure, reducing sample complexity.
result Localized sketching achieves sample complexity matching global sketching methods.

Improved privacy-preserving linear regression via iterative Hessian mixing.

problem Differentially private linear regression with improved accuracy and efficiency.
method Iterative Hessian Mixing (IHM) for differentially private ordinary least squares (DP-OLS).
result IHM provides better utility guarantees and outperforms AdaSSP in empirical evaluations.

Sketching, a dimensionality reduction technique, has received much attention in the statistics community. In this paper, we study sketching in the context of Newton's method for solving finite-sum optimization problems in which the number of variables and data points are both large. We study two forms of sketching that…

2017-05-17abs ↗pdf ↗

A new method reduces the bias in estimating inverse covariance matrices from sketches.

problem Reducing the bias in estimating inverse covariance matrices from sketches.
method Developed a framework for analyzing inversion bias and proposed a new sketching technique called LEverage Score Sparsified (LESS) embeddings.
result The new sketching technique reduces the inversion bias to O(1/d)O(1/\sqrt d) for m=O(d)m=O(d), significantly smaller than the Θ(1)Θ(1) approximation error.

We derive optimal statistical and computational complexity bounds for exp-concave stochastic minimization in terms of the effective dimension. For common eigendecay patterns of the population covariance matrix, this quantity is significantly smaller than the ambient dimension. Our results reveal interesting connections…

2018-05-21abs ↗pdf ↗

New guarantees for asymmetric sketching in compressive learning.

problem Statistical guarantees for compressive learning with asymmetric feature maps.
method Proves existing guarantees carry over to asymmetric scheme with LPD property, applies to quantized sketches.
result Existing statistical guarantees for compressive learning extend to asymmetric schemes with controlled error.

New technique debiases distributed optimization, improving convergence rate.

problem Bias in local estimates limits effectiveness of distributed second order optimization.
method Surrogate sketching and scaled regularization to eliminate bias.
result The debiased local estimates lead to faster convergence in distributed optimization.

The immense amount of daily generated and communicated data presents unique challenges in their processing. Clustering, the grouping of data without the presence of ground-truth labels, is an important tool for drawing inferences from data. Subspace clustering (SC) is a relatively recent method that is able to successf…

2017-07-22abs ↗pdf ↗

We consider statistical as well as algorithmic aspects of solving large-scale least-squares (LS) problems using randomized sketching algorithms. For a LS problem with input data (X,Y)Rn×p×Rn(X, Y) \in \mathbb{R}^{n \times p} \times \mathbb{R}^n, sketching algorithms use a sketching matrix, SRr×nS\in\mathbb{R}^{r \times n} with $r \…

2014-06-23abs ↗pdf ↗

Improved estimator for least squares using random projections achieves smaller error.

problem Improving the accuracy of least squares solutions for large-scale problems.
method James-Stein estimator applied to Gaussian sketching of least squares problems.
result Upper and lower bounds match when SNR is small and data matrix is well-conditioned.

DiffSketch combines privacy and communication efficiency in distributed learning.

problem Privacy and communication efficiency in distributed machine learning.
method DiffSketch uses Count Sketch for data stream summarization to achieve both privacy and efficiency.
result DiffSketch provides strong differential privacy guarantees and significant communication compression.