David Rumelhart is the unnamed hinge connecting the vault's schema-change cluster and its backpropagation-origins cluster — one trajectory from the 1978 tuning/restructuring taxonomy to the 1986 backprop revival

Two of the vault's clusters — moc-schema-change-and-restructuring and moc-backpropagation-origins — share a single author, and until now no note named him. The connection is not a resemblance of shape; it is a person.

Schema leg. The "tuning vs restructuring" vocabulary the vault leans on comes from Rumelhart & Norman (1978), "Accretion, tuning and restructuring: Three modes of learning" — the taxonomy recorded in claim-schema-change-four-mode-taxonomy and named as "the separate Rumelhart-Norman taxonomy" in claim-p3-indexes-prediction-error-schema-updating.

Backprop leg. The same David Rumelhart is the "R" in RHW 1986 and a co-leader of the PDP connectionist revival (claim-rhw-1986-demonstration-not-invention, claim-parker-1985-technical-report-not-cited) — the paradigm whose error-driven weight adjustment is the counter-mechanism to the symbolic-search combinatorial explosion the cluster's origin seed was about.

One trajectory. Rumelhart spent 1967–1987 in UCSD Psychology; his work ran from schema theory (1970s) into PDP and backpropagation (1986) as a single arc. Wikipedia frames the through-line: he was "an American psychologist who made many contributions to the formal analysis of human cognition, working primarily within the frameworks of mathematical psychology, symbolic artificial intelligence, and parallel distributed processing" (Tier 4, biographical/uncontested) — the same arc, from symbolic AI to PDP. So the vault's cognitive-science half and its history-of-ML half sit on two stages of one mind's lifework: how a knowledge structure changes under new evidence, formalized first as cognitive-psychology modes (1978), then as a neural-net algorithm (1986).

Scope limit. This note claims a shared author and one biographical arc. It does not claim Rumelhart deliberately carried the 1978 "tuning" concept into 1986 gradient-descent weight-tuning — the word recurs, but the deliberate through-line reading needs his own words and is left open at question-verify-rumelhart-schema-tuning-to-gradient-descent-through-line.