arXiv Computation and Language
Oct 9

Sparse Attention Is Matrix Approximation, Not Choosing from a Bag of Values

The paper argues that sparse attention should be viewed as a matrix approximation problem rather than merely selecting large scalar entries from the attention matrix. It introduces Matrix Approximation Sparse Attention (MASA), a method that replaces raw attention-mass ranking with a closed‑form score reflecting the reduction in matrix‑product approximation error. MASA can be integrated into existing sparse attention frameworks and, according to extensive experiments, consistently improves accuracy across various methods, benchmarks, and LLM backbones.

By Fang Wan, Xufeng Liu, Fan Li, Yi Liu