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 Statistical Learning


Exponential Error Convergence in Data Classification with Optimized Random Features: Acceleration by Quantum Machine Learning

arXiv.org Machine Learning

Random features are a central technique for scalable learning algorithms based on kernel methods. A recent work has shown that an algorithm for machine learning by quantum computer, quantum machine learning (QML), can exponentially speed up sampling of optimized random features, even without imposing restrictive assumptions on sparsity and low-rankness of matrices that had limited applicability of conventional QML algorithms; this QML algorithm makes it possible to significantly reduce and provably minimize the required number of features for regression tasks. However, a major interest in the field of QML is how widely the advantages of quantum computation can be exploited, not only in the regression tasks. We here construct a QML algorithm for a classification task accelerated by the optimized random features. We prove that the QML algorithm for sampling optimized random features, combined with stochastic gradient descent (SGD), can achieve state-of-the-art exponential convergence speed of reducing classification error in a classification task under a low-noise condition; at the same time, our algorithm with optimized random features can take advantage of the significant reduction of the required number of features so as to accelerate each iteration in the SGD and evaluation of the classifier obtained from our algorithm. These results discover a promising application of QML to significant acceleration of the leading classification algorithm based on kernel methods, without ruining its applicability to a practical class of data sets and the exponential error-convergence speed.


Costs and Benefits of Wasserstein Fair Regression

arXiv.org Machine Learning

Real-world applications of machine learning tools in high-stakes domains are often regulated to be fair, in the sense that the predicted target should satisfy some quantitative notion of parity with respect to a protected attribute. However, the exact tradeoff between fairness and accuracy with a real-valued target is not clear. In this paper, we characterize the inherent tradeoff between statistical parity and accuracy in the regression setting by providing a lower bound on the error of any fair regressor. Our lower bound is sharp, algorithm-independent, and admits a simple interpretation: when the moments of the target differ between groups, any fair algorithm has to make a large error on at least one of the groups. We further extend this result to give a lower bound on the joint error of any (approximately) fair algorithm, using the Wasserstein distance to measure the quality of the approximation. On the upside, we establish the first connection between individual fairness, accuracy parity, and the Wasserstein distance by showing that if a regressor is individually fair, it also approximately verifies the accuracy parity, where the gap is given by the Wasserstein distance between the two groups. Inspired by our theoretical results, we develop a practical algorithm for fair regression through the lens of representation learning, and conduct experiments on a real-world dataset to corroborate our findings.


Knowledge-Adaptation Priors

arXiv.org Machine Learning

Humans and animals have a natural ability to quickly adapt to their surroundings, but machine-learning models, when subjected to changes, often require a complete retraining from scratch. We present Knowledge-adaptation priors (K-priors) to reduce the cost of retraining by enabling quick and accurate adaptation for a wide-variety of tasks and models. This is made possible by a combination of weight and function-space priors to reconstruct the gradients of the past, which recovers and generalizes many existing, but seemingly-unrelated, adaptation strategies. Training with simple first-order gradient methods can often recover the exact retrained model to an arbitrary accuracy by choosing a sufficiently large memory of the past data. Empirical results confirm that the adaptation can be cheap and accurate, and a promising alternative to retraining.


Leveraging Probabilistic Circuits for Nonparametric Multi-Output Regression

arXiv.org Machine Learning

DN), thus, limiting their use to moderately sized data sets. To enable posterior inference in GPs on large-scale problems, Inspired by recent advances in the field of expertbased recent work (see e.g. Liu et al. [2020] for a detailed approximations of Gaussian processes (GPs), review) mainly resorts to global approximations to the posterior, we present an expert-based approach to large-scale e.g., using inducing points, or local approximations multi-output regression using single-output GP that aim to distribute the computation of the posterior distribution experts. Employing a deeply structured mixture onto local experts. Unfortunately, most of these of single-output GPs encoded via a probabilistic approaches only focus on single-output regression, i.e., the circuit allows us to capture correlations between dependent variable is univariate, and in the case of local multiple output dimensions accurately. By recursively approximations, do not easily extend to multi-output regression partitioning the covariate space and the output tasks, see Bruinsma et al. [2020] for a detailed space, posterior inference in our model reduces to discussion on recent techniques on multi-output GPs.


Directed Graph Embeddings in Pseudo-Riemannian Manifolds

arXiv.org Machine Learning

The inductive biases of graph representation learning algorithms are often encoded in the background geometry of their embedding space. In this paper, we show that general directed graphs can be effectively represented by an embedding model that combines three components: a pseudo-Riemannian metric structure, a non-trivial global topology, and a unique likelihood function that explicitly incorporates a preferred direction in embedding space. We demonstrate the representational capabilities of this method by applying it to the task of link prediction on a series of synthetic and real directed graphs from natural language applications and biology. In particular, we show that low-dimensional cylindrical Minkowski and anti-de Sitter spacetimes can produce equal or better graph representations than curved Riemannian manifolds of higher dimensions.


Non-PSD Matrix Sketching with Applications to Regression and Optimization

arXiv.org Machine Learning

A variety of dimensionality reduction techniques have been applied for computations involving large matrices. The underlying matrix is randomly compressed into a smaller one, while approximately retaining many of its original properties. As a result, much of the expensive computation can be performed on the small matrix. The sketching of positive semidefinite (PSD) matrices is well understood, but there are many applications where the related matrices are not PSD, including Hessian matrices in non-convex optimization and covariance matrices in regression applications involving complex numbers. In this paper, we present novel dimensionality reduction methods for non-PSD matrices, as well as their ``square-roots", which involve matrices with complex entries. We show how these techniques can be used for multiple downstream tasks. In particular, we show how to use the proposed matrix sketching techniques for both convex and non-convex optimization, $\ell_p$-regression for every $1 \leq p \leq \infty$, and vector-matrix-vector queries.


How to Do Hierarchical Clustering in Python ? 5 Easy Steps Only

#artificialintelligence

Hierarchical Clustering uses the distance based approach between the neighbor datapoints for clustering. Each data point is linked to its nearest neighbors. There are two ways you can do Hierarchical clustering Agglomerative that is bottom-up approach clustering and Divisive uses top-down approaches for clustering. In this tutorial, I will use the popular approach Agglomerative way. In order to find the number of subgroups in the dataset, you use dendrogram. It allows you to see linkages, relatedness using the tree graph. You will find many use cases for this type of clustering and some of them are DNA sequencing, Sentiment Analysis, Tracking Virus Diseases e.t.c. Popular Use Cases are Hospital Resource Management, Business Process Management, and Social Network Analysis. Here we are importing dendrogram, linkage, cluster, and cophenet from the scipy.cluster.hierarchy


PCA -- Machine Learning Algorithms with Implementation in Python

#artificialintelligence

Principal Component Analysis (PCA) is a Machine Learning algorithm used for various applications such as dimensionality reduction, data/image compression, feature extraction, and so on. The most common usage of PCA is dimensionality reduction (and we will see that in action below). PCA is basically used to extract/find patterns in a given dataset.


10 Best + Free Python Bootcamp 2021-Take This Course

#artificialintelligence

With the help of this list, all those learners who wish to learn all about Python Bootcamp can enroll in any of the suitable courses and start learning from it from the comfort of their homes, and that too for free. Below are the names and short descriptions of the 10 best and free Python Bootcamp courses for 2021. A Free Python Bootcamp Course course that will make you learn Python like a professional in no time. The Free Python Bootcamp course starts with the basics and then go all the way to creating your own applications and games. Throughout the Free Python Bootcamp course, you will be learning a variety of topics that will make you a professional at developing different applications and games. The instructor has delivered all the learning content that will help you learn both Python 2 and Python 3. Starting the Free Python Bootcamp course, you will learn to create games with Python.


A Markov Reward Process-Based Approach to Spatial Interpolation

arXiv.org Artificial Intelligence

The interpolation of spatial data can be of tremendous value in various applications, such as forecasting weather from only a few measurements of meteorological or remote sensing data. Existing methods for spatial interpolation, such as variants of kriging and spatial autoregressive models, tend to suffer from at least one of the following limitations: (a) the assumption of stationarity, (b) the assumption of isotropy, and (c) the trade-off between modelling local or global spatial interaction. Addressing these issues in this work, we propose the use of Markov reward processes (MRPs) as a spatial interpolation method, and we introduce three variants thereof: (i) a basic static discount MRP (SD-MRP), (ii) an accurate but mostly theoretical optimised MRP (O-MRP), and (iii) a transferable weight prediction MRP (WP-MRP). All variants of MRP interpolation operate locally, while also implicitly accounting for global spatial relationships in the entire system through recursion. Additionally, O-MRP and WP-MRP no longer assume stationarity and are robust to anisotropy. We evaluated our proposed methods by comparing the mean absolute errors of their interpolated grid cells to those of 7 common baselines, selected from models based on spatial autocorrelation, (spatial) regression, and deep learning. We performed detailed evaluations on two publicly available datasets (local GDP values, and COVID-19 patient trajectory data). The results from these experiments clearly show the competitive advantage of MRP interpolation, which achieved significantly lower errors than the existing methods in 23 out of 40 experimental conditions, or 35 out of 40 when including O-MRP.