Multi-Label Learning to Rank through Multi-Objective Optimization

Abstract

Learning to Rank (LTR) technique is ubiquitous in Information Retrieval systems, especially in search ranking applications. The relevance labels used to train ranking models are often noisy measurements of human behavior, such as product ratings in product searches. This results in non-unique ground truth rankings and ambiguity. To address this, Multi-Label LTR (MLLTR) is used to train models using multiple relevance criteria, capturing conflicting but important goals, such as product quality and purchase likelihood for improved revenue in product searches. This research leverages Multi-Objective Optimization (MOO) in MLLTR and employs modern MOO algorithms to solve the problem. A general framework is proposed to combine label information to characterize trade-offs among goals, and allows for the use of gradient-based MOO algorithms. We test the proposed framework on four publicly available LTR datasets and one E-commerce dataset to show its efficacy.