Geert Jan Olsder was a member of Kwakernaak's Twente Systems and Control group until 1982

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A 2025 University of Twente obituary for Huibert Kwakernaak names Geert Jan Olsder as one of the members who grew Kwakernaak's Systems and Control research group "to the point that it belonged to the top of the world in Systems and Control," with a parenthetical end-date of 1982 (before Olsder's later career at TU Delft).

This sharpens what the vault previously knew only in narrower terms — that Olsder co-authored a single 1976 population-planning paper with R.C.W. Strijbos (claim-clark-2016-dutch-authors-identifiable-as-olsder-and-strijbos) and independently gave a 2024 eyewitness account of meeting Song Jian (claim-olsder-eyewitness-account-confirms-song-jian-at-1978-helsinki-ifac-congress). Those facts placed Olsder at Twente without saying how long, or in what standing. This claim establishes he was a formal group member until 1982 — a tenure covering both the 1976 paper and the 1978 Helsinki congress — organizational colleague of Kwakernaak, not merely a co-author who happened to overlap in one paper. The obituary names no start date for Olsder's membership, so when it began is not established here.