Song Jian's Moscow control-theory teacher was A.A. Fel'dbaum

song-jianfeldbaumcyberneticscontrol-theorycold-war-sciencebiographyperson-bridge

Song Jian's biography has been read in this vault several times over — the 1978 Helsinki IFAC congress, the 1962 cybernetics lab recruitment by Qian Xuesen, the Twente contact disputes — without anyone naming the specific person who taught him control theory during his earlier 1953 posting to the USSR. Susan Greenhalgh's own account names him directly: "Song studied with the world-famous control theorist A. A. Fel'dbaum, received an associate PhD degree from Moscow University, and published seven papers in Russian on the theory of optimal control." Greenhalgh's own footnote 14 attributes the biography paragraph carrying this sentence to Huang Shouzeng, "Song Jian jianli" ("Brief biography of Song Jian"), in Song Jian, Selected Scientific Papers, pp. 744–752 — so the teacher fact ultimately rests on an official biography published with Song's collected papers, one layer beneath Greenhalgh's account. This sits chronologically before the 1962/1975/1978 contacts the vault's Song Jian cluster otherwise documents — Song's Soviet training is the earliest node in his control-theory formation, not a later acquisition.

The name had already surfaced once in this vault, informally, in the commentary of claim-song-jian-missile-scientist-engineered-one-child-policy-via-cybernetics-of-population ("Song trained under Fel'dbaum, one mathematical step from Pontryagin") — an aside, not a sourced claim. This note formalizes it with the primary quote and gives Fel'dbaum his own page, entity-aa-feldbaum, where his own subsequent work is described (claim-feldbaum-1960s-dual-control-formalized-exploration-exploitation-tradeoff).