David Parker's 1985 backprop rediscovery was an internal MIT technical report (TR-47), credited by RHW 1986 only as "personal communication" with no reference entry

Parker's independent 1985 rediscovery of backpropagation took the form of an internal MIT working paper — "Learning-Logic: Casting the Cortex of the Human Brain in Silicon," Technical Report TR-47 — not a journal article, conference paper, or preprint. The citation asymmetry inside the 1986 Nature paper is the sharp detail (from the direct OCR read behind claim-rhw-1986-reference-list-four-works): RHW credit Parker only as "(personal communication)," with no entry in their numbered reference list, while Yann LeCun gets a citable footnote. The asymmetry is itself evidence — Parker's report wasn't circulating as citable print in mid-1986.

Left open, honestly: who David Parker was — his profession, why he moved between a Stanford tech-licensing office (1982) and an MIT research center (1985) — is [unverified — could not confirm or deny after search]. That is a person-page question, and per standing rule person material is Cali-gated; Parker is not on the entity-candidates ledger until there's public biographical material to anchor him. This note is about the document and the citation, not the man. See moc-backpropagation-origins, claim-reverse-mode-multiple-independent-discovery.