Enhancing Online Ranking Systems via Multi-SurfaceCo-Training for Content Understanding

Gwendolyn Zhao
Yilin Zheng
Raghu Keshavan
Lukasz Heldt
Qian Sun
Fabio Soldo
Li Wei
Aniruddh Nath
Dapo Omidiran
Rein Zhang
Mei Chen
Lichan Hong
2025

Abstract

Content understanding is an important part in real-world recommendation systems. This paper introduces a Multi-surface Co-training (MulCo) system, designed to enhance online ranking systems by improving content understanding. The model is trained through a task-aligned co-training approach, leveraging objectives and data from multiple surfaces and various pre-trained em-beddings. It separates video content understanding into an offline model, enabling scalability and efficient resource use. Experiments demonstrate that MulCo significantly outperforms non-task-aligned pre-trained embeddings and achieves substantial gains in online satisfied engagement metrics. This system presents a practical solution to improve content understanding in multi-surface large-scale recommender systems.
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