Teiji Takagi | |
|---|---|
 | |
| Born | (1875-04-21)April 21, 1875 Kazuya village nearGifu |
| Died | February 28, 1960(1960-02-28) (aged 84) |
| Nationality | Japanese |
| Alma mater | Tokyo Imperial University |
| Known for | Takagi curve Takagi existence theorem Autonne–Takagi factorization |
| Scientific career | |
| Fields | Mathematics |
| Institutions | Tokyo Imperial University |
| Doctoral advisor | David Hilbert |
| Doctoral students | Shokichi Iyanaga[1] Sigekatu Kuroda[1] Tadasi Nakayama[1] Kenjiro Shoda[1] |
Teiji Takagi (高木 貞治Takagi Teiji, April 21, 1875 – February 28, 1960) was a Japanesemathematician, best known for proving theTakagi existence theorem inclass field theory. TheBlancmange curve, the graph of a nowhere-differentiable butuniformly continuous function, is also called the Takagi curve after his work on it.
He was born in the rural area of theGifu Prefecture,Japan. He began learning mathematics in middle school, reading texts in English since none were available in Japanese. After attending a high school for gifted students, he went on to theImperial University (University of Tokyo), at that time the only university in Japan before theImperial University System was established on June 18, 1897. There he learned mathematics from such European classic texts asSalmon'sAlgebra andWeber'sLehrbuch der Algebra. Aided byHilbert, he then studied atGöttingen. Aside from his work inalgebraic number theory he wrote a great number of Japanese textbooks on mathematics and geometry.
During World War I, he was isolated from European mathematicians and developed his existence theorem in class field theory, building on the work of Heinrich Weber. As an Invited Speaker, he presented a synopsis of this research in a talkSur quelques théoremes généraux de la théorie des nombres algébriques[2] at theInternational Congress of Mathematicians inStrasbourg in 1920. There he found little recognition of the value of his research, since algebraic number theory was then studied mainly in Germany and German mathematicians were excluded from the Congress. Takagi published his theory in the same year in the journal of the University of Tokyo. However, the significance of Takagi's work was first recognized byEmil Artin in 1922, and was again pointed out byCarl Ludwig Siegel, and at the same time byHelmut Hasse, who lectured in Kiel in 1923 on class field theory and presented Takagi's work in a lecture at the meeting of theDMV in 1925 inDanzig and in hisKlassenkörperbericht (class field report) in the 1926 annual report of the DMV. Takagi was then internationally recognized as one of the world's leading number theorists. In 1932 he was vice-president of theInternational Congress of Mathematicians inZürich and in 1936 was a member of the selection committee for the firstFields Medal.
He was also instrumental duringWorld War II in the development of Japanese encryption systems; seePurple.
TheAutonne-Takagi factorization of complex symmetric matrices is named in his honour.
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