Talagrand (2018) states, of his own field's history, that automatic-differentiation and optimization researchers 'had little contact' — a participant's account, from meteorology, of the cross-community unawareness pattern the vault documents between ML and AD

automatic-differentiationhistory-of-mlmultiple-discoverymeteorologydata-assimilationoptimal-controladjoint-methodbackpropagation-gap

Olivier Talagrand's 2018 ECMWF symposium reminiscence of 4D-Var's genesis states, of the broader development of adjoint-based gradient codes after his own field's success with the method:

"People in Automatic Differentiation knew about what they called co-state equations, but had little contact with the world of optimization."

This is the same structural mechanism the vault already documents between machine learning and automatic differentiation (claim-ml-and-ad-communities-mutually-unaware, quoting Baydin et al. 2018: "Until very recently, the fields of machine learning and AD have largely been unaware of each other...") — but stated about a different pair of communities (AD and optimization, not ML and AD), independently, by a working meteorologist describing his own field's history rather than drawn from any ML-history source. It is a further account the vault holds of essentially this sentence — after Baydin et al. 2018 (a survey's summary, not first-person testimony) and Griewank 2012 (an AD participant's history) — this one a meteorologist's reminiscence of his own field's encounters with AD: two literatures holding the same mathematical object under different names, without citation traffic between them. The pattern it extends is the same one Griewank's five-field list documents from the AD side — when literatures don't read each other, the same object gets reinvented, or at least re-walled, once per field.

This claim stands on its own: it is a statement about unawareness between AD and optimization, not a claim that 4D-Var itself was independently discovered. That separate (and considerably weaker) claim is addressed and corrected in claim-4d-var-adjoint-method-transmitted-not-independent.