🎯Core Definition
PLE (Progressive Layered Extraction, proposed by Tencent PCG at RecSys 2020 Best Paper) is a breakthrough multi-task recommendation architecture that eliminates Negative Transfer and Seesaw Phenomena; instead of indiscriminately sharing all experts across all tasks like MMoE, PLE explicitly bifurcates the expert pool into two distinct classes: 1) Task-Specific Experts (dedicated exclusively to a single objective, e.g., CTR-only or CVR-only); 2) Shared Experts (capturing universal commonalities); using multi-layer cascading Customized Gate Control (CGC) blocks, PLE progressively separates task-specific parameters from shared parameters layer-by-layer.
💡Use Cases
Heavy ranking across multi-objective entertainment feeds (Tencent Video, WeChat Channels, TikTok) optimizing Click, Like, Share, Complete View, and Purchase.
⚡Key Problems Solved
MMoE suffers severe 'Seesaw Phenomena' (improving one task degrades another) when task correlations are heterogeneous; PLE's physical isolation of task-specific and shared experts mathematically guarantees conflict-free multi-task representation learning.