On Applying Dimension Reduction for Multi-labeled Problems

摘要

Traditional classification problem assumes that a data sample belongs to one class among the predefined classes. On the other hand, in a multi-labeled problem such as text categorization, data samples can belong to multiple classes and the task is to output a set of class labels associated with new unseen data sample. As common in text categorization problem, learning a classifier in a high dimensional space can be difficult, known as the curse of dimensionality. It has been shown that performing dimension reduction as a preprocessing step can improve classification performances greatly. Especially, Linear discriminant analysis (LDA) is one of the most popular dimension reduction methods, which is optimized for classification tasks. However, in applying LDA for a multi-labeled problem some ambiguities and difficulties can arise. In this paper, we study on applying LDA for a multi-labeled problem and analyze how an objective function of LDA can be interpreted in multi-labeled setting. We also propose a LDA algorithm which is effective in a multi-labeled problem. Experimental results demonstrate that by considering multi-labeled structures LDA can achieve computational efficiency and also improve classification performances greatly.