Polynomial, trigonometric, and tropical activations

Fuente: arXiv
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Main Authors: Khalfaoui-Hassani, Ismail, Kesselheim, Stefan
Format: Preprint
Published: 2025
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author Khalfaoui-Hassani, Ismail
Kesselheim, Stefan
author_facet Khalfaoui-Hassani, Ismail
Kesselheim, Stefan
contents Which functions can be used as activations in deep neural networks? This article explores families of functions based on orthonormal bases, including the Hermite polynomial basis and the Fourier trigonometric basis, as well as a basis resulting from the tropicalization of a polynomial basis. Our study shows that, through simple variance-preserving initialization and without additional clamping mechanisms, these activations can successfully be used to train deep models, such as GPT-2 for next-token prediction on OpenWebText and ConvNeXt for image classification on ImageNet. Our work addresses the issue of exploding and vanishing activations and gradients, particularly prevalent with polynomial activations, and opens the door for improving the efficiency of large-scale learning tasks. Furthermore, our approach provides insight into the structure of neural networks, revealing that networks with polynomial activations can be interpreted as multivariate polynomial mappings. Finally, using Hermite interpolation, we show that our activations can closely approximate classical ones in pre-trained models by matching both the function and its derivative, making them especially useful for fine-tuning tasks. These activations are available in the torchortho library via: https://github.com/K-H-Ismail/torchortho.
format Preprint
id arxiv_https___arxiv_org_abs_2502_01247
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Polynomial, trigonometric, and tropical activations
Khalfaoui-Hassani, Ismail
Kesselheim, Stefan
Machine Learning
Artificial Intelligence
Computation and Language
Computer Vision and Pattern Recognition
Algebraic Geometry
Which functions can be used as activations in deep neural networks? This article explores families of functions based on orthonormal bases, including the Hermite polynomial basis and the Fourier trigonometric basis, as well as a basis resulting from the tropicalization of a polynomial basis. Our study shows that, through simple variance-preserving initialization and without additional clamping mechanisms, these activations can successfully be used to train deep models, such as GPT-2 for next-token prediction on OpenWebText and ConvNeXt for image classification on ImageNet. Our work addresses the issue of exploding and vanishing activations and gradients, particularly prevalent with polynomial activations, and opens the door for improving the efficiency of large-scale learning tasks. Furthermore, our approach provides insight into the structure of neural networks, revealing that networks with polynomial activations can be interpreted as multivariate polynomial mappings. Finally, using Hermite interpolation, we show that our activations can closely approximate classical ones in pre-trained models by matching both the function and its derivative, making them especially useful for fine-tuning tasks. These activations are available in the torchortho library via: https://github.com/K-H-Ismail/torchortho.
title Polynomial, trigonometric, and tropical activations
topic Machine Learning
Artificial Intelligence
Computation and Language
Computer Vision and Pattern Recognition
Algebraic Geometry
url https://arxiv.org/abs/2502.01247