Statistical Learning
Honey Bee Dance Modeling in Real-time using Machine Learning
Saghafi, Abolfazl, Tsokos, Chris P.
The waggle dance that honeybees perform is an astonishing way of communicating the location of food source. After over 60 years of its discovery, researchers still use manual labeling by watching hours of dance videos to detect different transitions between dance components thus extracting information regarding the distance and direction to the food source. We propose an automated process to monitor and segment different components of honeybee waggle dance. The process is highly accurate, runs in real-time, and can use shared information between multiple dances. Keywords: Classification, Machine Learning, Honey Bee, Real-time 1. Introduction Honey bees perform a special dance known as waggle dance within the beehive to communicate the information regarding the distance and direction of food sources.
Stochastic Recursive Gradient Algorithm for Nonconvex Optimization
Nguyen, Lam M., Liu, Jie, Scheinberg, Katya, Takรกฤ, Martin
In this paper, we study and analyze the mini-batch version of StochAstic Recursive grAdient algoritHm (SARAH), a method employing the stochastic recursive gradient, for solving empirical loss minimization for the case of nonconvex losses. We provide a sublinear convergence rate (to stationary points) for general nonconvex functions and a linear convergence rate for gradient dominated functions, both of which have some advantages compared to other modern stochastic gradient algorithms for nonconvex losses.
Kernel-based Reconstruction of Space-time Functions on Dynamic Graphs
Romero, Daniel, Ioannidis, Vassilis N., Giannakis, Georgios B.
Abstract--Graph-based methods pervade the inference toolk-its of numerous disciplines including sociology, biology, neuroscience, physics, chemistry, and engineering. A challenging problem encountered in this context pertains to determining the attributes of a set of vertices given those of another subset at possibly different time instants. Leveraging spatiotemporal dynamics can drastically reduce the number of observed vertices, and hence the cost of sampling. Alleviating the limited flexibility of existing approaches, the present paper broadens the existing kernel-based graph function reconstruction framework to accommodate time-evolving functions over possibly time-evolving topologies. This approach inherits the versatility and generality of kernel-based methods, for which no knowledge on distributions or second-order statistics is required. Systematic guidelines are provided to construct two families of space-time kernels with complementary strengths. The first facilitates judicious control of regularization on a space-time frequency plane, whereas the second can afford time-varying topologies. Batch and online estimators are also put forth, and a novel kernel Kalman filter is developed to obtain these estimates at affordable computational cost. Numerical tests with real data sets corroborate the merits of the proposed methods relative to competing alternatives. A number of applications involving social, biological, brain, sensor, transportation, or communication networks call for efficient methods to infer the attributes of some vertices given the attributes of other vertices [1]. For example, in a social network with vertices and edges respectively representing persons and friendships, one may be interested in determining an individual's consumption trends based on those of their friends. This task emerges when sampling cost constraints, such as the impossibility to poll one country's entire population about political orientation, limit the number of vertices with known attributes. Existing approaches typically formulate this problem as the reconstruction of a function or signal on a graph [1]-[6], and rely on its smoothness with respect to the graph, in the sense that neighboring vertices have similar function values. This principle suggests, for instance, estimating one person's age by looking at their friends' age.
Demystifying ResNet
Li, Sihan, Jiao, Jiantao, Han, Yanjun, Weissman, Tsachy
The Residual Network (ResNet), proposed in He et al. (2015), utilized shortcut connections to significantly reduce the difficulty of training, which resulted in great performance boosts in terms of both training and generalization error. It was empirically observed in He et al. (2015) that stacking more layers of residual blocks with shortcut 2 results in smaller training error, while it is not true for shortcut of length 1 or 3. We provide a theoretical explanation for the uniqueness of shortcut 2. We show that with or without nonlinearities, by adding shortcuts that have depth two, the condition number of the Hessian of the loss function at the zero initial point is depth-invariant, which makes training very deep models no more difficult than shallow ones. Shortcuts of higher depth result in an extremely flat (high-order) stationary point initially, from which the optimization algorithm is hard to escape. The shortcut 1, however, is essentially equivalent to no shortcuts, which has a condition number exploding to infinity as the number of layers grows. We further argue that as the number of layers tends to infinity, it suffices to only look at the loss function at the zero initial point. Extensive experiments are provided accompanying our theoretical results. We show that initializing the network to small weights with shortcut 2 achieves significantly better results than random Gaussian (Xavier) initialization, orthogonal initialization, and shortcuts of deeper depth, from various perspectives ranging from final loss, learning dynamics and stability, to the behavior of the Hessian along the learning process.
How To Interpret R-squared and Goodness-of-Fit in Regression Analysis
This article was written by Jim Frost from Minitab. He came to Minitab with a background in a wide variety of academic research. His role was the "data/stat guy" on research projects that ranged from osteoporosis prevention to quantitative studies of online user behavior. Essentially, his job was to design the appropriate research conditions, accurately generate a vast sea of measurements, and then pull out patterns and meanings from it. After you have fit a linear model using regression analysis, ANOVA, or design of experiments (DOE), you need to determine how well the model fits the data. To help you out, Minitab statistical software presents a variety of goodness-of-fit statistics.
Bayesian Machine Learning, Explained
So you know the Bayes rule. How does it relate to machine learning? It can be quite difficult to grasp how the puzzle pieces fit together - we know it took us a while. This article is an introduction we wish we had back then. While we have some grasp on the matter, we're not experts, so the following might contain inaccuracies or even outright errors. Feel free to point them out, either in the comments or privately.
A Tour of Machine Learning Algorithms
Let's take a look at three different learning styles in machine learning algorithms: Input data is called training data and has a known label or result such as spam/not-spam or a stock price at a time. Example problems are clustering, dimensionality reduction and association rule learning. They are concerned with building much larger and more complex neural networks and, as commented on above, many methods are concerned with semi-supervised learning problems where large datasets contain very little labeled data. Like clustering methods, dimensionality reduction seek and exploit the inherent structure in the data, but in this case in an unsupervised manner or order to summarize or describe data using less information.
Ensemble Machine Learning in Python: Random Forest, AdaBoost
In recent years, we've seen a resurgence in AI, or artificial intelligence, and machine learning. Machine learning has led to some amazing results, like being able to analyze medical images and predict diseases on-par with human experts. Google's AlphaGo program was able to beat a world champion in the strategy game go using deep reinforcement learning. Machine learning is even being used to program self driving cars, which is going to change the automotive industry forever. Imagine a world with drastically reduced car accidents, simply by removing the element of human error.
Support Vector Machines: A Concise Technical Overview
Classification is concerned with building a model that separates data into distinct classes. This model is built by inputting a set of training data for which the classes are pre-labeled in order for the algorithm to learn from. The model is then used by inputting a different dataset for which the classes are withheld, allowing the model to predict their class membership based on what it has learned from the training set. Well-known classification schemes include decision trees and Support Vector Machines, among a whole host of others. As this type of algorithm requires explicit class labeling, classification is a form of supervised learning.