In Memory of Professor Emeritus Heisuke Hironaka

It is with heavy hearts that we say farewell to Professor Emeritus Heisuke Hironaka, who passed away in March, 2026 at the age of 94. He received his graduate degree from Harvard in 1960 under the direction of Oscar Zariski and, after holding positions at Brandeis and Columbia universities, joined the Harvard faculty in 1968.

Hironaka was one of the premier algebraic geometers of the 20th century. He was best known for his 1964 work on the resolution of certain singularities and torus embeddings with implications in the theory of analytic functions, and complex and Kähler manifolds. For this work, Hironaka was awarded the Fields Medal in 1970. He is one of the most widely known and acclaimed scholars in Japan, where he has had a broad influence on society and education. In 1975, he was awarded the Order of Culture of the Japanese government by the Emperor.

While at Harvard, Hironaka held a joint professorship at Kyoto University. He went on to become director of the Research Institute for Mathematical Sciences in Kyoto (1983-1985) and president of Yamaguchi University (1996-2002), which is in the same prefecture where he was born. Hironaka contributed a lot of time and effort to encouraging young people interested in mathematics. In 1980, he started a summer seminar for Japanese high school students and later added one for Japanese and American college students. In 1984, he established a philanthropic foundation called the Japan Association for Mathematical Sciences, which provides fellowships for Japanese students to pursue doctoral studies abroad. He also played an important role in founding the international Kyoto Prize which, since 1984, has been awarded annually in advanced technology, basic sciences, arts, and philosophy.

In 2011, Hironaka was awarded the Harvard Kenneth C. Griffin Graduate School of Arts and Sciences (GSAS) Centennial Medal. It is the highest honor that the Harvard Griffin GSAS bestows to celebrate the achievements of a select group of Harvard University’s most accomplished alumni whose contributions to knowledge, to their disciplines, to their colleagues, and to society at large have made a fundamental and lasting impact.

When asked “Why do you do mathematics?” in a 2005 interview he gave for the “Notices of the AMS,” Hironaka’s response was: “I accumulate anything to do with numbers. For instance, I have more than 10,000 photos of flowers and leaves. I like to just count the numbers and compare them. I am so pleased to be a mathematician, because I can see the mathematical interest in things.”