LeCun's own retrospective describes his 1985 algorithm as propagating "virtual target values," not gradients, with no control-theory framing

yann-lecunpaul-werbosarthur-brysonbackpropagationpriority-vs-paternityhistory-of-ml

On his own research page, in the section describing his PhD work, Yann LeCun characterizes the mechanism of his 1985 paper — commonly cited as "Une procédure d'apprentissage pour réseau à seuil asymétrique," Proc. Cognitiva 85, Paris, pp. 599–604 — directly: "Although a special form of my algorithm was equivalent to backpropagation it was based on backpropagating 'virtual target values' for the hidden units rather than gradients." Nowhere in this passage, or elsewhere on the page, does LeCun describe the 1985 method as invoking control theory, duality theory, or Bryson and Ho.

This bears directly on claim-werbos-2004-object-nets-patent-names-lecun-against-1994-book, which quotes Paul Werbos's 2004 "Object Nets" patent characterizing LeCun's 1985 paper as deriving backpropagation "from an application of duality theory from control theory (Bryson and Ho, 1969)." LeCun's own first-person account of his own work is a direct, self-interested-the-other-way source — he has no obvious stake in minimizing the control-theory framing of his own early work — and it does not corroborate Werbos's characterization. It instead describes a different mechanism (target propagation rather than gradient propagation) for the 1985 paper specifically.

The primary text of the 1985 Cognitiva paper itself was not located or read this session (no digitized copy found via BibBase, archive.org, Gallica, HAL, or general web search), so the question of whether the paper cites Bryson and Ho directly remains open — see question-does-lecuns-1985-derivation-match-werboss-duality-theory-characterization. What this note establishes is narrower: the one available first-person account of the 1985 paper's content contradicts the premise that it was a gradient-based, duality-theory derivation at all.