Does Pontryagin's 1956 maximum-principle announcement genuinely predate Kelley (1960) as an independent Cold War discovery, and did Boltyanskii/Gamkrelidze/Mishchenko's 1956 work already contain the co-state/adjoint backward-gradient equation?

The 2026-07-11 capture 10-inbox/raw/2026-07-11-hop-pontryagin-backprop-bridge.md claimed that Pontryagin's maximum principle was "first announced" in 1956 ("On the Theory of Optimal Processes"), predating the American Kelley (1960) precursor the vault already documents in claim-kelley-bryson-optimal-control-precursor, and that the two schools developed independently and roughly contemporaneously with Bellman's dynamic programming. The capture itself flagged this [unverified-quant/mechanism -- needs primary] and rested it only on Wikipedia (Tier 4) — below the sourcing floor for a contested, load-bearing priority claim (00-meta/specs/sources.md, historical/biographical escalation rule).

The vault's existing Pontryagin note (claim-pontryagin-worked-blind-via-mothers-spoken-symbol-glosses) already describes the maximum principle as formalized with Boltyanskii, Gamkrelidze, and Mishchenko and dates its Lenin Prize to 1962, but does not pin down a 1956 first-announcement date or state the precedence-over-Kelley claim explicitly. This question was not promoted to a claim-note because the core Soviet-twin bridge is already on the shelf and the added precedence detail does not clear the sourcing floor on its own.

What would answer this: a primary or Tier 1–2 source for the 1956 announcement — Pontryagin, Boltyanskii, Gamkrelidze, and Mishchenko's own 1956 paper or a scholarly history of optimal control (e.g. Pesch & Plail's history-of-the-maximum-principle papers, or the Boltyanskii/Gamkrelidze memoir literature) — confirming (a) the 1956 date, (b) that the co-state/ adjoint backward equation was present at that point (not only in the fuller 1962 book The Mathematical Theory of Optimal Processes), and (c) whether Kelley or Bryson had any awareness of the Soviet work before 1960/1961.

Candidate next moves: search for an English-language history-of-control- theory paper that cites the original 1956 Doklady Akademii Nauk SSSR note; check whether Recht's "Mates of Costate" (claim-recht-adjoints-equivalence-not-transmission) or Mizutani-Dreyfus- Nishio 2000 (claim-backprop-special-case-kelley-bryson-formula) date the Soviet side at all (neither currently does, per the notes read at promotion time).