Learning Compact Embedding Layers via Differentiable Product Quantization

Ting Chen, Lala Li, Yizhou Sun

TL;DR: We propose a differentiable product quantization framework that can reduce the size of embedding layer in an end-to-end training at no performance cost.

Abstract: Embedding layers are commonly used to map discrete symbols into continuous embedding vectors that reflect their semantic meanings. Despite their effectiveness, the number of parameters in an embedding layer increases linearly with the number of symbols and poses a critical challenge on memory and storage constraints. In this work, we propose a generic and end-to-end learnable compression framework termed differentiable product quantization (DPQ). We present two instantiations of DPQ that leverage different approximation techniques to enable differentiability in end-to-end learning. Our method can readily serve as a drop-in alternative for any existing embedding layer. Empirically, DPQ offers significant compression ratios (14-238x) at negligible or no performance cost on 10 datasets across three different language tasks.

Keywords: efficient modeling, compact embedding, embedding table compression, differentiable product quantization