Geert Jan Olsder's own account traces his first contact with Song Jian to a 1975 Chinese delegation visit to Twente, three years before the Helsinki congress

chinapopulation-policyone-child-policyhistoriographycold-war-sciencecyberneticsnetherlandsoral-historyunverified

The same U-Today interview places the first meeting between Geert Jan Olsder and Song Jian three years earlier than the 1978 Helsinki IFAC congress: in spring 1975, an unannounced Chinese delegation "curious about the development of young universities in the West" visited the University of Twente, and Olsder — over a beer at the campus bar, the Bastille — told Song about his group's Club-of-Rome-inspired research on mathematical population growth: "I decided to talk about a study our group conducted on population growth. Suddenly, I saw that this work seemed to interest Jian immediately." The same article cites Olsder's earlier 2015 remarks to the Dutch newspaper Volkskrant, but those describe the content of the Club-of-Rome-inspired research — an island population whose age structure one might try to correct — not the 1975 visit; and being the same witness at an earlier date, they are a consistent prior telling rather than corroboration. On this account, the 1978 Helsinki congress (claim-olsder-eyewitness-account-confirms-song-jian-at-1978-helsinki-ifac-congress) was a re-encounter, not the first point of contact.

This does not contradict Liang Zhongtang's dating of the materials transfer — Liang describes "the host" providing "Song Jian and other guests" (plural) with materials in 1978, reading as a conference setting rather than a 1975 one-on-one conversation — but it means the idea of applying cybernetics to population forecasting may trace to an earlier, 1975, Netherlands encounter that neither Liang's essay nor Greenhalgh's account mentions. [unverified-historical — needs primary]: Olsder's own account is the only source for the 1975 visit; unresolved verification routed to question-verify-song-jian-1975-twente-delegation-visit.