BEP: A Binary Error Propagation Algorithm for Binary Neural Networks Training

Fuente: arXiv
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Hauptverfasser: Colombo, Luca, Pittorino, Fabrizio, Zambon, Daniele, Baldassi, Carlo, Roveri, Manuel, Alippi, Cesare
Format: Preprint
Veröffentlicht: 2025
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author Colombo, Luca
Pittorino, Fabrizio
Zambon, Daniele
Baldassi, Carlo
Roveri, Manuel
Alippi, Cesare
author_facet Colombo, Luca
Pittorino, Fabrizio
Zambon, Daniele
Baldassi, Carlo
Roveri, Manuel
Alippi, Cesare
contents Binary Neural Networks (BNNs), which constrain both weights and activations to binary values, offer substantial reductions in computational complexity, memory footprint, and energy consumption. These advantages make them particularly well suited for deployment on resource-constrained devices. However, training BNNs via gradient-based optimization remains challenging due to the discrete nature of their variables. The dominant approach, quantization-aware training, circumvents this issue by employing surrogate gradients. Yet, this method requires maintaining latent full-precision parameters and performing the backward pass with floating-point arithmetic, thereby forfeiting the efficiency of binary operations during training. While alternative approaches based on local learning rules exist, they are unsuitable for global credit assignment and for back-propagating errors in multi-layer architectures. This paper introduces Binary Error Propagation (BEP), the first learning algorithm to establish a principled, discrete analog of the backpropagation chain rule. This mechanism enables error signals, represented as binary vectors, to be propagated backward through multiple layers of a neural network. BEP operates entirely on binary variables, with all forward and backward computations performed using only bitwise operations. Crucially, this makes BEP the first solution to enable end-to-end binary training for recurrent neural network architectures. We validate the effectiveness of BEP on both multi-layer perceptrons and recurrent neural networks, demonstrating gains of up to +6.89% and +10.57% in test accuracy, respectively. The proposed algorithm is released as an open-source repository.
format Preprint
id arxiv_https___arxiv_org_abs_2512_04189
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle BEP: A Binary Error Propagation Algorithm for Binary Neural Networks Training
Colombo, Luca
Pittorino, Fabrizio
Zambon, Daniele
Baldassi, Carlo
Roveri, Manuel
Alippi, Cesare
Machine Learning
Disordered Systems and Neural Networks
Artificial Intelligence
I.2.6
Binary Neural Networks (BNNs), which constrain both weights and activations to binary values, offer substantial reductions in computational complexity, memory footprint, and energy consumption. These advantages make them particularly well suited for deployment on resource-constrained devices. However, training BNNs via gradient-based optimization remains challenging due to the discrete nature of their variables. The dominant approach, quantization-aware training, circumvents this issue by employing surrogate gradients. Yet, this method requires maintaining latent full-precision parameters and performing the backward pass with floating-point arithmetic, thereby forfeiting the efficiency of binary operations during training. While alternative approaches based on local learning rules exist, they are unsuitable for global credit assignment and for back-propagating errors in multi-layer architectures. This paper introduces Binary Error Propagation (BEP), the first learning algorithm to establish a principled, discrete analog of the backpropagation chain rule. This mechanism enables error signals, represented as binary vectors, to be propagated backward through multiple layers of a neural network. BEP operates entirely on binary variables, with all forward and backward computations performed using only bitwise operations. Crucially, this makes BEP the first solution to enable end-to-end binary training for recurrent neural network architectures. We validate the effectiveness of BEP on both multi-layer perceptrons and recurrent neural networks, demonstrating gains of up to +6.89% and +10.57% in test accuracy, respectively. The proposed algorithm is released as an open-source repository.
title BEP: A Binary Error Propagation Algorithm for Binary Neural Networks Training
topic Machine Learning
Disordered Systems and Neural Networks
Artificial Intelligence
I.2.6
url https://arxiv.org/abs/2512.04189