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Forman, G., Scholz, M. & Rajaram, S., 2009. Feature Shaping for Linear SVM Classifiers. Paris, France: ACM Press.
Abstract: Linear classiers have been shown to be eective for many discrimination tasks. Irrespective of the learning algorithm itself, the nal classier has a weight to multiply by each feature. This suggests that ideally each input feature should be linearly correlated with the target variable (or anti-correlated), whereas raw features may be highly non-linear. In this paper, we attempt to re-shape each input feature so that it is appropriate to use with a linear weight and to scale the dierent features in proportion to their predictive value. We demonstrate that this pre-processing is benecial for linear SVM classiers on a large benchmark of text classication tasks as well as UCI datasets.
Keywords: DataMiningGeneral; SupportVectorMachines
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Ghanty, P., Paul, S. & Pal, N.R., 2009. NEUROSVM: An Architecture to Reduce the Effect of the Choice of Kernel on the Performance of SVM, Journal of Machine Learning Research, 10, p. 591–622.
Abstract: In this paper we propose a new multilayer classifier architecture. The proposed hybrid architecture has two cascaded modules: feature extraction module and classification module. In the feature extraction module we use the multilayered perceptron (MLP) neural networks, although other tools such as radial basis function (RBF) networks can be used. In the classification module we use support vector machines (SVMs)—here also other tool such as MLP or RBF can be used. The feature extraction module has several sub-modules each of which is expected to extract features capturing the discriminating characteristics of different areas of the input space. The classification module classifies the data based on the extracted features. The resultant architecture with MLP in feature extraction module and SVM in classification module is called NEUROSVM. The NEUROSVM is tested on twelve benchmark data sets and the performance of the NEUROSVMis found to be better than both MLP and SVM. We also compare the performance of proposed architecture with that of two ensemble methods: majority voting and averaging. Here also the NEUROSVM is found to perform better than these two ensemble methods. Further we explore the use of MLP and RBF in the classification module of the proposed architecture. The most attractive feature of NEUROSVM is that it practically eliminates the severe dependency of SVM on the choice of kernel. This has been verified with respect to both linear and non-linear kernels. We have also demonstrated that for the feature extraction module, the full training of MLPs is not needed.
Keywords: DimReduction; NeuralNets; SupportVectorMachines
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Huang, F.J. & LeCun, Y., 2006. Large-scale Learning with SVM and Convolutional Nets for Generic Object Categorization.
Abstract: The detection and recognition of generic object categories with invariance to viewpoint, illumination, and clutter requires the combination of a feature extractor and a classifier. We show that architectures such as convolutional networks are good at learning invariant features, but not always optimal for classification, while Support Vector Machines are good at producing decision surfaces from wellbehaved feature vectors, but cannot learn complicated invariances. We present a hybrid system where a convolutional network is trained to detect and recognize generic objects, and a Gaussian-kernel SVMis trained from the features learned by the convolutional network. Results are given on a large generic object recognition task with six categories (human figures, four-legged animals, airplanes, trucks, cars, and “none of the above”), with multiple instances of each object category under various poses, illuminations, and backgrounds. On the test set, which contains different object instances than the training set, an SVM alone yields a 43.3% error rate, a convolutional net alone yields 7.2% and an SVM on top of features produced by the convolutional net yields 5.9%.
Keywords: NeuralNets; SupportVectorMachines
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Jiang, B., Zhang, X. & Cai, T., 2008. Estimating the Confidence Interval for Prediction Errors of Support Vector Machine Classifiers, Journal of Machine Learning Research, 9, p. 521–540.
Abstract: Support vector machine (SVM) is one of the most popular and promising classification algorithms. After a classification rule is constructed via the SVM, it is essential to evaluate its prediction accuracy. In this paper, we develop procedures for obtaining both point and interval estimators for the prediction error. Under mild regularity conditions, we derive the consistency and asymptotic normality of the prediction error estimators for SVM with finite-dimensional kernels. A perturbationresampling procedure is proposed to obtain interval estimates for the prediction error in practice. With numerical studies on simulated data and a benchmark repository, we recommend the use of interval estimates centered at the cross-validated point estimates for the prediction error. Further applications of the proposed procedure in model evaluation and feature selection are illustrated with two examples.
Keywords: SupportVectorMachines
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Klinkenberg, R.. Predicting Phases in Business Cycles Under Concept Drift.
Abstract: For many tasks where data is collected over an extended period of time, its underlying distribution is likely to change. A typical example is information filtering, i.e. the adaptive classification of documents with respect to a particular user interest. Both the interest of the user and the document content change over time. Machine learning approaches handling this type of concept drift have been shown to outperform more static approaches ignoring it in experiments with different types of simulated concept drifts on real-word text data. In this paper, these approaches to learning drifting concepts are applied to the problem of classifying phases in business cycles. Their performance is compared to the more static approaches on real-world data for this classification task, in order to evaluate whether this domain also exhibits concept drifts and whether the concept drift approaches also allow performance gains in this domain. While previous studies were based on simulated concept drift scenarios, the experiments in this domain are not based on any simulated drift, but on the real concept drift inherent to this real-world data. Hence this paper provides significant support for the applicability of the proposed machine learning approaches to handling concept drift in realworld problems.
Keywords: FinanceGeneral; SupportVectorMachines
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Kumar, M. & Thenmozhi, T.. Forecasting Stock Index Movement: A Comparison of Support Vector Machines and Random Forest.
Abstract: There exists vast research articles which predict the stock market as well pricing of stock index financial instruments but most of the proposed models focus on the accurate forecasting of the levels (i.e. value) of the underlying stock index. There is a lack of studies examining the predictability of the direction / sign of stock index movement. Given the notion that a prediction with little forecast error does not necessarily translate into capital gain, this study is an attempt to predict the direction of S&P CNX NIFTY Market Index of the National Stock Exchange, one of the fastest growing financial exchanges in developing Asian countries. Random forest and Support Vector Machines (SVM) are very specific type of machine learning method, and are promising tools for the prediction of financial time series. The tested classification models, which predict direction, include linear discriminant analysis, logit, artificial neural network, random forest and SVM. Empirical experimentation suggests that the SVM outperforms the other classification methods in terms of predicting the direction of the stock market movement and random forest method outperforms neural network, discriminant analysis and logit model used in this study.
Keywords: SupportVectorMachines
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Lin, C.-J., Weng, R.C. & Keerthi, S.S., 2008. Trust Region Newton Method for Large-Scale Logistic Regression, Journal of Machine Learning Research, 9, p. 627–650.
Abstract: Large-scale logistic regression arises in many applications such as document classification and natural language processing. In this paper, we apply a trust region Newton method to maximize the log-likelihood of the logistic regression model. The proposed method uses only approximate Newton steps in the beginning, but achieves fast convergence in the end. Experiments show that it is faster than the commonly used quasi Newton approach for logistic regression. We also extend the proposed method to large-scale L2-loss linear support vector machines (SVM).
Keywords: LargeScaleLearning; SupportVectorMachines
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Lin, H.-T. & Li, L., 2008. Support Vector Machinery for Inifinite Ensemble Learning, Journal of Machine Learning Research, 9, p. 285–312.
Keywords: Ensembles; SupportVectorMachines
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