arXiv Machine Learning
Sep 2

Performance-Efficiency Tradeoffs in Transformers: An Approximation Theory Perspective

The paper examines how to allocate attention heads and head dimensions across Transformer layers to balance expressivity and efficiency. It provides a mathematical analysis of early layers’ role in information extraction and characterizes the trade‑off between head count and dimension under a fixed parameter budget. The authors prove a saturation effect of softmax activations, showing that increasing head dimensions yields diminishing returns, especially for long sequences, and propose strategies for efficient parameter allocation across layers.

By Ruoxi Yu, Haotian Jiang, Jingpu Cheng, Penghao Yu, Qianxiao Li, Zhong Li
arXiv Machine Learning
Oct 12

Data-Adaptive Mahalanobis Metric Learning for Cross-Head Attention in Transformers

The paper introduces Data-Adaptive Mahalanobis Cross-Head Attention (DAMCHA), a new attention mechanism that extends Multi-Head Attention by learning a full cross-head metric matrix and adapting it to input data. DAMCHA captures inter-head interactions beyond the block-diagonal structure of standard MHA and uses input-dependent parameterization for dynamic attention geometry. The authors provide regularization techniques, such as stack-wise parameter sharing, to maintain efficiency and stability, and report that DAMCHA-based Transformers outperform baselines on several benchmarks.

By Zhenke Duan, Xin Li, Jiqun Pan, Dong Xiaofei, Hanwen Ning, Xinyuan Song