Statistical Learning
VICReg: Variance-Invariance-Covariance Regularization for Self-Supervised Learning
Bardes, Adrien, Ponce, Jean, LeCun, Yann
Recent self-supervised methods for image representation learning are based on maximizing the agreement between embedding vectors from different views of the same image. A trivial solution is obtained when the encoder outputs constant vectors. This collapse problem is often avoided through implicit biases in the learning architecture, that often lack a clear justification or interpretation. In this paper, we introduce VICReg (Variance-Invariance-Covariance Regularization), a method that explicitly avoids the collapse problem with a simple regularization term on the variance of the embeddings along each dimension individually. VICReg combines the variance term with a decorrelation mechanism based on redundancy reduction and covariance regularization, and achieves results on par with the state of the art on several downstream tasks. In addition, we show that incorporating our new variance term into other methods helps stabilize the training and leads to performance improvements.
Inference attacks: How much information can machine learning models leak?
The widespread adoption of machine learning models in different applications has given rise to a new range of privacy and security concerns. Among them are'inference attacks', whereby attackers cause a target machine learning model to leak information about its training data. However, these attacks are not very well understood and we need to readjust our definitions and expectations of how they can affect our privacy. This is according to researchers from several academic institutions in Australia and India who made the warning in a new paper (PDF) accepted at the IEEE European Symposium on Security and Privacy, which will be held in September. The paper was jointly authored by researchers at the University of New South Wales; Birla Institute of Technology and Science, Pilani; Macquarie University; and the Cyber & Electronic Warfare Division, Defence Science and Technology Group, Australia.
Your Guide for the Commonly Used Machine Learning Algorithms
We are currently living in such a period where computing has transformed immensely from large mainframes to personal computers to the cloud. The constant technological progress and the evolution in computing resulted in major automation. In this article, let's understand few commonly used machine learning algorithms. These can be used for almost any kind of data problem. This is used to estimate real values like the cost of houses, number of calls, total sales, and many more based on a continuous variable.
Hill Climbing and Simulated Annealing AI Algorithms
Redeem Get Udemy Coupon What you'll learn Udemy Coupon Best Description Search Algorithms and Optimization techniques are the engines of most Artificial Intelligence techniques and Data Science. There is no doubt that Hill Climbing and Simulated Annealing are the most well-regarded and widely used AI search techniques. A lot of scientists and practitioners use search and optimization algorithms without understanding their internal structure. However, understanding the internal structure and mechanism of such AI problem-solving techniques will allow them to solve problems more efficiently. This also allows them to tune, tweak, and even design new algorithms for different projects.
[2021] Learn Python for Data Science A-Z
Do you want to make your career in Data Science? Want to have a successful career and a life worth inspiring? All you need is the will to succeed and the passion to learn!!! Python being one of the most widely used languages is the new mantra for success. It is the number one tool for analytical professionals and is one of the top programming languages in the year 2019. Our aim is to make the students get acquainted with python and become proficient in the most popular programming language.
The challenges and realities of retailing in a COVID-19 world: Identifying trending and Vital During Crisis keywords during Covid-19 using Machine Learning (Austria as a case study)
Al., Reda Mastouri Et, Gilkey, Joseph
From global pandemics to geopolitical turmoil, leaders in logistics, product allocation, procurement and operations are facing increasing difficulty with safeguarding their organizations against supply chain vulnerabilities. It is recommended to opt for forecasting against trending based benchmark because auditing a future forecast puts more focus on seasonality. The forecasting models provide with end-to-end, real time oversight of the entire supply chain, while utilizing predictive analytics and artificial intelligence to identify potential disruptions before they occur. By combining internal and external data points, coming up with an AI-enabled modelling engine can greatly reduce risk by helping retail companies proactively respond to supply and demand variability. This research paper puts focus on creating an ingenious way to tackle the impact of COVID19 on Supply chain, product allocation, trending and seasonality. Key words: Supply chain, covid-19, forecasting, coronavirus, manufacturing, seasonality, trending, retail.
Exact Recovery in the General Hypergraph Stochastic Block Model
Zhang, Qiaosheng, Tan, Vincent Y. F.
This paper investigates fundamental limits of exact recovery in the general d-uniform hypergraph stochastic block model (d-HSBM), wherein n nodes are partitioned into k disjoint communities with relative sizes (p1,..., pk). Each subset of nodes with cardinality d is generated independently as an order-d hyperedge with a certain probability that depends on the ground-truth communities that the d nodes belong to. The goal is to exactly recover the k hidden communities based on the observed hypergraph. We show that there exists a sharp threshold such that exact recovery is achievable above the threshold and impossible below the threshold (apart from a small regime of parameters that will be specified precisely). This threshold is represented in terms of a quantity which we term as the generalized Chernoff-Hellinger divergence between communities. Our result for this general model recovers prior results for the standard SBM and d-HSBM with two symmetric communities as special cases. En route to proving our achievability results, we develop a polynomial-time two-stage algorithm that meets the threshold. The first stage adopts a certain hypergraph spectral clustering method to obtain a coarse estimate of communities, and the second stage refines each node individually via local refinement steps to ensure exact recovery.
Distribution-free calibration guarantees for histogram binning without sample splitting
Gupta, Chirag, Ramdas, Aaditya K.
In classification, the goal is to learn a model that uses observed feature measurements to make a class prediction on the categorical outcome. However, for safety-critical areas such as medicine and finance, a single class prediction might be insufficient and reliable measures of confidence or certainty may be desired. Such uncertainty quantification is often provided by predictors that produce not just a class label, but a probability distribution over the labels. If the predicted probability distribution is consistent with observed empirical frequencies of labels, the predictor is said to be calibrated [Dawid, 1982]. In this paper we study the problem of calibration for binary classification; let X and Y " t0, 1u denote the feature and label spaces. We focus on the recalibration or post-hoc calibration setting, a standard statistical setting where the goal is to recalibrate existing ('pre-learnt') classifiers that are powerful and (statistically) efficient for classification accuracy, but do not satisfy calibration properties out-of-the-box. This setup is popular for recalibrating pre-trained deep nets. For example, Guo et al. [2017, Figure 4] demonstrated that a pre-learnt ResNet is initially miscalibrated, but can be effectively post-hoc calibrated. In the case of binary classification, the pre-learnt model can be any arbitrary function that provides a classification'score' g: X Ñ r0, 1s.
On projection methods for functional time series forecasting
Elías, Antonio, Jiménez, Raúl, Shang, Hanlin
Two nonparametric methods are presented for forecasting functional time series (FTS). The FTS we observe is a curve at a discrete-time point. We address both one-step-ahead forecasting and dynamic updating. Dynamic updating is a forward prediction of the unobserved segment of the most recent curve. Among the two proposed methods, the first one is a straightforward adaptation to FTS of the $k$-nearest neighbors methods for univariate time series forecasting. The second one is based on a selection of curves, termed \emph{the curve envelope}, that aims to be representative in shape and magnitude of the most recent functional observation, either a whole curve or the observed part of a partially observed curve. In a similar fashion to $k$-nearest neighbors and other projection methods successfully used for time series forecasting, we ``project'' the $k$-nearest neighbors and the curves in the envelope for forecasting. In doing so, we keep track of the next period evolution of the curves. The methods are applied to simulated data, daily electricity demand, and NOx emissions and provide competitive results with and often superior to several benchmark predictions. The approach offers a model-free alternative to statistical methods based on FTS modeling to study the cyclic or seasonal behavior of many FTS.
Gradient-based Bayesian Experimental Design for Implicit Models using Mutual Information Lower Bounds
Kleinegesse, Steven, Gutmann, Michael U.
We introduce a framework for Bayesian experimental design (BED) with implicit models, where the data-generating distribution is intractable but sampling from it is still possible. In order to find optimal experimental designs for such models, our approach maximises mutual information lower bounds that are parametrised by neural networks. By training a neural network on sampled data, we simultaneously update network parameters and designs using stochastic gradient-ascent. The framework enables experimental design with a variety of prominent lower bounds and can be applied to a wide range of scientific tasks, such as parameter estimation, model discrimination and improving future predictions. Using a set of intractable toy models, we provide a comprehensive empirical comparison of prominent lower bounds applied to the aforementioned tasks.