---
title: "backpropagation"
type: "entity"
entity_kind: "concept"
status: "hub"
canonical_name: "backpropagation"
aliases: ["backprop","back-propagation","the backward pass"]
first_seen: "2026-05-31T00:00:00.000Z"
writer_model: "claude-opus-4-8"
connects_to: ["reverse-mode automatic differentiation","credit assignment","gradient descent","connectionism","priority vs paternity"]
---


The vault's single most-referenced concept and the gravitational center of
its largest cluster. The recurring finding is that "backpropagation" names a
result with no clean inventor: reverse-mode automatic differentiation
(Linnainmaa 1970), optimal-control adjoint methods (Kelley 1960, Bryson 1961),
independent derivations (Werbos 1974, Parker), and the RHW 1986 *demonstration*
that made it famous all sit on the same algorithm reached from different
fields. The through-line the vault keeps sharpening is *priority vs paternity*
— who had it first vs who made it matter — and the citation culture that lets
substantive priority go unacknowledged. See [[moc-backpropagation-origins]]
for the full map.

## References
- [[moc-backpropagation-origins]] · [[backpropagation-gap]] · [[claim-rhw-1986-demonstration-not-invention]] · [[claim-linnainmaa-priority-not-paternity]] · [[claim-kelley-bryson-optimal-control-precursor]] · [[claim-werbos-backprop-from-freud-own-account]] · [[claim-reverse-mode-multiple-independent-discovery]]
- Related hubs: [[entity-seppo-linnainmaa]] · [[entity-paul-werbos]] · [[entity-geoffrey-hinton]] · [[entity-david-rumelhart]] · [[entity-automatic-differentiation]]