Support Vector Machines
Linear centralization classifier
Bonyadi, Mohammad Reza, Vegh, Viktor, Reutens, David C.
A classification algorithm, called the Linear Centralization Classifier (LCC), is introduced. The algorithm seeks to find a transformation that best maps instances from the feature space to a space where they concentrate towards the center of their own classes, while maximimizing the distance between class centers. We formulate the classifier as a quadratic program with quadratic constraints. We then simplify this formulation to a linear program that can be solved effectively using a linear programming solver (e.g., simplex-dual). We extend the formulation for LCC to enable the use of kernel functions for non-linear classification applications. We compare our method with two standard classification methods (support vector machine and linear discriminant analysis) and four state-of-the-art classification methods when they are applied to eight standard classification datasets. Our experimental results show that LCC is able to classify instances more accurately (based on the area under the receiver operating characteristic) in comparison to other tested methods on the chosen datasets. We also report the results for LCC with a particular kernel to solve for synthetic non-linear classification problems.
Auto-tuning data science--new research streamlines machine learning
The tremendous recent growth of data science--both as a discipline and an application--can be attributed, in part, to its robust problem-solving power: It can predict when credit card transactions are fraudulent, help business owners figure out when to send coupons in order to maximize customer response, or facilitate educational interventions by forecasting when a student is on the cusp of dropping out. To get to these data-driven solutions, though, data scientists must shepherd their raw data through a complex series of steps, each one requiring many human-driven decisions. The last step in the process, deciding on a modeling technique, is particularly crucial. There are hundreds of techniques to choose from--from neural networks to support vector machines--and selecting the best one can mean millions of dollars of additional revenue, or the difference between spotting a flaw in critical medical devices and missing it. In a paper called "ATM: A distributed, collaborative, scalable system for automated machine learning," which was presented last week at the IEEE International Conference on Big Data, researchers from MIT and Michigan State University present a new system that automates the model selection step, even improving on human performance.
Adversarial Structured Prediction for Multivariate Measures
Wang, Hong, Rezaei, Ashkan, Ziebart, Brian D.
Many predicted structured objects (e.g., sequences, matchings, trees) are evaluated using the F-score, alignment error rate (AER), or other multivariate performance measures. Since inductively optimizing these measures using training data is typically computationally difficult, empirical risk minimization of surrogate losses is employed, using, e.g., the hinge loss for (structured) support vector machines. These approximations often introduce a mismatch between the learner's objective and the desired application performance, leading to inconsistency. We take a different approach: adversarially approximate training data while optimizing the exact F-score or AER. Structured predictions under this formulation result from solving zero-sum games between a predictor seeking the best performance and an adversary seeking the worst while required to (approximately) match certain structured properties of the training data. We explore this approach for word alignment (AER evaluation) and named entity recognition (F-score evaluation) with linear-chain constraints.
Support vector comparison machines
Venuto, David, Hocking, Toby Dylan, Sphanurattana, Lakjaree, Sugiyama, Masashi
In ranking problems, the goal is to learn a ranking function from labeled pairs of input points. In this paper, we consider the related comparison problem, where the label indicates which element of the pair is better, or if there is no significant difference. We cast the learning problem as a margin maximization, and show that it can be solved by converting it to a standard SVM. We use simulated nonlinear patterns, a real learning to rank sushi data set, and a chess data set to show that our proposed SVMcompare algorithm outperforms SVMrank when there are equality pairs.
MIT's automated machine learning works 100x faster than human data scientists
A new automated machine learning system can analyze data and come up with a solution 100x faster than humans, according to a new paper from MIT and Michigan State University. This could potentially help businesses take advantage of machine learning's capabilities in a faster, easier way, while also filling data science talent gaps. The system also potentially marks a tipping point in machine learning adoption in the enterprise, which is expected to double in 2018, as TechRepublic's sister site ZDNet reported. When seeking a solution to a problem, data scientists must wade through huge datasets, and choose the modeling technique they believe will work best. The issue is, there are hundreds of techniques to choose from, including neural networks and support vector machines, and choosing the best one could potentially mean the difference between millions of dollars in ad revenue or none, or catching a flaw in a medical device or not.
Avoiding Synchronization in First-Order Methods for Sparse Convex Optimization
Devarakonda, Aditya, Fountoulakis, Kimon, Demmel, James, Mahoney, Michael W.
Parallel computing has played an important role in speeding up convex optimization methods for big data analytics and large-scale machine learning (ML). However, the scalability of these optimization methods is inhibited by the cost of communicating and synchronizing processors in a parallel setting. Iterative ML methods are particularly sensitive to communication cost since they often require communication every iteration. In this work, we extend well-known techniques from Communication-Avoiding Krylov subspace methods to first-order, block coordinate descent methods for Support Vector Machines and Proximal Least-Squares problems. Our Synchronization-Avoiding (SA) variants reduce the latency cost by a tunable factor of $s$ at the expense of a factor of $s$ increase in flops and bandwidth costs. We show that the SA-variants are numerically stable and can attain large speedups of up to $5.1\times$ on a Cray XC30 supercomputer.
Understanding Career Progression in Baseball Through Machine Learning
Bierig, Brian, Hollenbeck, Jonathan, Stroud, Alexander
Abstract-- Professional baseball players are increasingly guaranteed expensive long-term contracts, with over 70 deals signed in excess of $90 million, mostly in the last decade. These are substantial sums compared to a typical franchise valuation of $1-2 billion. Hence, the players to whom a team chooses to give such a contract can have an enormous impact on both competitiveness and profit. Despite this, most published approaches examining career progression in baseball are fairly simplistic. We applied four machine learning algorithms to the problem and soundly improved upon existing approaches, particularly for batting data. I. INTRODUCTION The typical mode of entry for a player into baseball is through the first-year player draft. Players usually enter the draft immediately after high school or college and then spend several years in the drafting team's minor league system. When deemed ready, the drafting team can promote the player to the Major Leagues.
Highly Efficient Human Action Recognition with Quantum Genetic Algorithm Optimized Support Vector Machine
Liu, Yafeng, Feng, Shimin, Zhao, Zhikai, Ding, Enjie
In this paper we propose the use of quantum genetic algorithm to optimize the support vector machine (SVM) for human action recognition. The Microsoft Kinect sensor can be used for skeleton tracking, which provides the joints' position data. However, how to extract the motion features for representing the dynamics of a human skeleton is still a challenge due to the complexity of human motion. We present a highly efficient features extraction method for action classification, that is, using the joint angles to represent a human skeleton and calculating the variance of each angle during an action time window. Using the proposed representation, we compared the human action classification accuracy of two approaches, including the optimized SVM based on quantum genetic algorithm and the conventional SVM with grid search. Experimental results on the MSR-12 dataset show that the conventional SVM achieved an accuracy of $ 93.85\% $. The proposed approach outperforms the conventional method with an accuracy of $ 96.15\% $.
Machine learning: Supervised methods (PDF Download Available)
We'll illustrate SVM using a two-class problem and begin with Typically, C is chosen using cross-validation2. Points at the margin's edge (black outlines) are called The margin is now 0.64 with six support vectors. AU: the title is long and a bit clunky. What do you think about deleting'supervised methods' from it?
Predicting Station-level Hourly Demands in a Large-scale Bike-sharing Network: A Graph Convolutional Neural Network Approach
Lin, Lei, He, Zhengbing, Peeta, Srinivas, Wen, Xuejin
Bike sharing is a vital piece in a modern multi-modal transportation system. However, it suffers from the bike unbalancing problem due to fluctuating spatial and temporal demands. Accurate bike sharing demand predictions can help operators to make optimal routes and schedules for bike redistributions, and therefore enhance the system efficiency. In this study, we propose a novel Graph Convolutional Neural Network with Data-driven Graph Filter (GCNN-DDGF) model to predict station-level hourly demands in a large-scale bike-sharing network. With each station as a vertex in the network, the new proposed GCNN-DDGF model is able to automatically learn the hidden correlations between stations, and thus overcomes a common issue reported in the previous studies, i.e., the quality and performance of GCNN models rely on the predefinition of the adjacency matrix. To show the performance of the proposed model, this study compares the GCNN-DDGF model with four GCNNs models, whose adjacency matrices are from different bike sharing system matrices including the Spatial Distance matrix (SD), the Demand matrix (DE), the Average Trip Duration matrix (ATD) and the Demand Correlation matrix (DC), respectively. The five types of GCNN models and the classic Support Vector Regression model are built on a Citi Bike dataset from New York City which includes 272 stations and over 28 million transactions from 2013 to 2016. Results show that the GCNN-DDGF model has the lowest Root Mean Square Error, followed by the GCNN-DC model, and the GCNN-ATD model has the worst performance. Through a further examination, we find the learned DDGF captures some similar information embedded in the SD, DE and DC matrices, and it also uncovers more hidden heterogeneous pairwise correlations between stations that are not revealed by any of those matrices.