On the Mathematical Relationship Between Layer Normalization and Dynamic Activation Functions

Fuente: arXiv
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Autore principale: Stollenwerk, Felix
Natura: Preprint
Pubblicazione: 2025
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author Stollenwerk, Felix
author_facet Stollenwerk, Felix
contents Layer normalization (LN) is an essential component of modern neural networks. While many alternative techniques have been proposed, none of them have succeeded in replacing LN so far. The latest suggestion in this line of research is a dynamic activation function called Dynamic Tanh (DyT). Although it is empirically well-motivated and appealing from a practical point of view, it lacks a theoretical foundation. In this work, we shed light on the mathematical relationship between LN and dynamic activation functions. In particular, we derive DyT from the LN variant RMSNorm, and show that a well-defined decoupling in derivative space as well as an approximation are needed to do so. By applying the same decoupling procedure directly in function space, we are able to omit the approximation and obtain the exact element-wise counterpart of RMSNorm, which we call Dynamic Inverse Square Root Unit (DyISRU). We demonstrate numerically that DyISRU reproduces the normalization effect on outliers more accurately than DyT does.
format Preprint
id arxiv_https___arxiv_org_abs_2503_21708
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Mathematical Relationship Between Layer Normalization and Dynamic Activation Functions
Stollenwerk, Felix
Machine Learning
Artificial Intelligence
Computation and Language
Layer normalization (LN) is an essential component of modern neural networks. While many alternative techniques have been proposed, none of them have succeeded in replacing LN so far. The latest suggestion in this line of research is a dynamic activation function called Dynamic Tanh (DyT). Although it is empirically well-motivated and appealing from a practical point of view, it lacks a theoretical foundation. In this work, we shed light on the mathematical relationship between LN and dynamic activation functions. In particular, we derive DyT from the LN variant RMSNorm, and show that a well-defined decoupling in derivative space as well as an approximation are needed to do so. By applying the same decoupling procedure directly in function space, we are able to omit the approximation and obtain the exact element-wise counterpart of RMSNorm, which we call Dynamic Inverse Square Root Unit (DyISRU). We demonstrate numerically that DyISRU reproduces the normalization effect on outliers more accurately than DyT does.
title On the Mathematical Relationship Between Layer Normalization and Dynamic Activation Functions
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2503.21708