Title: Incorporating label-wise thresholding and class-imbalanced strategy into binary relevance for online multi-label classification

Authors: Kunyong Hu; Tingting Zhai

Addresses: College of Information Engineering, Jiangsu Province Engineering Research Center of Knowledge Management and Intelligent Service, Yangzhou University, Yangzhou, 225127, China ' College of Information Engineering, Jiangsu Province Engineering Research Center of Knowledge Management and Intelligent Service, Yangzhou University, Yangzhou, 225127, China

Abstract: Binary relevance (BR) is widely used to solve multi-label classification problems. Typically, all binary classifiers in BR use a shared global fixed threshold to convert predicted values to binary classification results. However, some studies disclosed that tuning a separate threshold per label is better than a fixed global threshold. Given this discovery, in this paper, we adaptively train a thresholding model for the scoring model of each binary classifier in BR. By solving an online convex optimisation problem that minimises a logistic loss function, both models can be updated simultaneously. Furthermore, each binary classifier may suffer from the class-imbalance problem. To this end, we design three cost-sensitive strategies to adjust the misclassification cost of relevant and irrelevant labels for each binary classifier. An efficient closed-form update can be obtained by solving our formulated problem. Extensive experiments on multiple datasets demonstrate that our methods outperform other state-of-the-art methods.

Keywords: online multi-label classification; binary relevance; adaptive label thresholding; class-imbalance; cost-sensitive learning.

DOI: 10.1504/IJIIDS.2024.141766

International Journal of Intelligent Information and Database Systems, 2024 Vol.16 No.4, pp.409 - 425

Received: 08 Jul 2023
Accepted: 09 Apr 2024
Published online: 01 Oct 2024 *

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