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Ogura Kinnosuke

Japanese Historian of Mathematics

Ogura Kinnosuke (1882–1962) was a Japanese mathematician and historian of mathematics who made lasting contributions to the study of number theory and the history of East Asian mathematics. Trained in modern Western mathematics, Ogura also devoted himself to recovering and analyzing Japan’s indigenous mathematical tradition, Wasan.

His research in number theory included work on congruences and Diophantine equations, which involve finding integer solutions to polynomial equations such as: \ These investigations connected him to classical problems in arithmetic while also reflecting the influence of modern algebraic number theory.

As a historian, Ogura published important studies on the development of Wasan, including the works of Seki Takakazu and his successors. By applying rigorous historical methods, he demonstrated how Japanese mathematicians independently developed theories of determinants, infinite series, and algebraic equations. His comparative studies highlighted both the originality and limitations of Wasan relative to European traditions.

Ogura’s dual role as mathematician and historian made him a key figure in shaping Japan’s intellectual self-understanding during the 20th century. He ensured that Japan’s indigenous contributions were not forgotten while also promoting the integration of Japanese mathematics into the global history of science.