Vertical Semi-Federated Learning for Efficient Online Advertising
Traditional vertical federated learning (VFL) is constrained by the sample-overlap assumption and incurs high real-time inference overhead, rendering it ill-suited for online advertising. To address these limitations, this paper proposes Semi-VFL—a novel vertical semi-federated learning paradigm that eliminates the requirement for sample overlap and enables modeling over the full sample space. We design a Joint Privileged Learning (JPL) framework coupled with cross-party representation distillation to jointly train on both overlapping and non-overlapping data. Furthermore, we introduce a lightweight single-party student model and cross-party feature correlation modeling to balance prediction accuracy, inference efficiency, and feasibility of localized deployment. Evaluated on real-world advertising datasets, Semi-VFL consistently outperforms state-of-the-art baselines, achieving significant improvements in AUC, queries-per-second (QPS), and deployment flexibility.