Radon Measure Representations for Infinite-Width Neural Networks with Singular Activations

Abstract

The theoretical foundation of infinite-width shallow neural networks relies heavily on continuous integral representations and Barron spaces. Recently, harmonic analysis-specifically the Radon and Ridgelet transforms-has emerged as a powerful tool to invert these representations and compute the optimal network weights. However, a major analytical bottleneck remains: standard neural network activation functions exhibit severe spectral singularities at the frequency origin. To bypass this divergence, existing frameworks either restrict the theory to specific activation families or mathematically quotient out the network's affine components, which inherently limits their practical scope. In this paper, we overcome these limitations by introducing a purely distributional framework for the generalized Radon transform R $σ$ that operates on a broad class of tempered distribution activation functions. By defining a regularized spectrum formulation g($ρ$) = (i$ρ$) $α$ $σ$($ρ$), we rigorously absorb the origin singularities without truncating the underlying functional space. Building upon this exact reconstruction, we show that under a definite parity assumption on the activation, there exists an exact linear isometry between Barron functions and their optimal weight measures.