>>888 追加

https://sites.google.com/site/sendailogichomepage/files/ref/ref_07
仙台ロジック倶楽部
数学基礎論と消えたパラドックス 田中一之 数学セミナー 　1993.8
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■ Ｈ. フリードマンの定理
代数構造まで含めてユークリッドの反例になるものはあまりなさそうな気がしてくるのだが、
その感覚をひっくり返したのが フリードマンである(1973)．

　言葉の説明を後回しにして、定理を述べる．

ペアノの算術の可算な超準モデルは、自らと同型な接頭部を持つ．

■ おまけ
H. フリードマンは 1967年に１８歳でスタンフォード大に入った．

しかし、並の秀才と少し違うのは、このとき助教授として入ったことである．

彼はすでにその前に２階算術について画期的な仕事をしてMITから博士号をとっている．

https://en.wikipedia.org/wiki/Harvey_Friedman
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Harvey Friedman (born 23 September 1948)[1] is an American mathematical logician at Ohio State University in Columbus, Ohio. He has worked on reverse mathematics, a project intended to derive the axioms of mathematics from the theorems considered to be necessary.
In recent years this has advanced to a study of Boolean relation theory, which attempts to justify large cardinal axioms by demonstrating their necessity for deriving certain propositions considered "concrete".

Friedman earned his Ph.D. from the Massachusetts Institute of Technology in 1967, with a dissertation on Subsystems of Analysis. His advisor was Gerald Sacks. Friedman received the Alan T. Waterman Award in 1984. He delivered the Tarski Lectures in 2007.

In 1967, Friedman was listed in the Guinness Book of World Records for being the world's youngest professor when he taught at Stanford University at age 18 as an assistant professor of philosophy.[1][2][3] He has also been a professor of mathematics and a professor of music.[4]