The Bitvector Machine: A Fast and Robust Machine Learning Algorithm for Non-linear Problems

In this paper we present and evaluate a simple but effective machine learning algorithm that we call Bitvector Machine: Feature vectors are partitioned along component-wise quantiles and converted into bitvectors that are learned. It is shown that the method is efficient in both training and classification. The effectiveness of the method is analysed theoretically for best and worst-case scenarios. Experiments on high-dimensional synthetic and real world data show a huge speed boost compared to Support Vector Machines with RBF kernel. By tabulating kernel functions, computing medians in linear-time, and exploiting modern processor technology for advanced bitvector operations, we achieve a speed-up of 32 for classification and 48 for kernel evaluation compared to the popular LIBSVM. Although the method does not generally outperform a SVM with RBF kernel it achieves a high classification accuracy and has qualitative advantages over the linear classifier.