hidden-neuron-delta-recursive-from-downstream

IN premise — entries/2026/06/21/wiki-Backpropagation-chunk-4.md

Created 2026-06-21T09:55:49+00:00

For hidden neurons, δ_j = (Σ_ℓ w_jℓ · δ_ℓ) · φ'(net_j) — the error signal is computed recursively as a weighted sum of downstream δ values, which is the mechanism that gives backpropagation its name.