**Tosio Kato** was a Japanese mathematician who worked in partial differential equations, mathematical physics and functional analysis.

- This innocent little comment in fact hides a period of great difficulty and suffering for Kato.
- This last paper contains one of Kato's most important results, namely the self-adjointness of Hamiltonians of Schrödinger type.
- After Kato was awarded his doctorate he was appointed as assistant professor of physics at the University of Tokyo in 1951.
- In 1954-55 Kato visited the United States for the first time, spending time at the University of California at Berkeley, and at New York University.
- The Department of Mathematics of the University of California, Berkeley, published Kato's notes Quadratic forms in Hilbert spaces and asymptotic perturbation series in 1955.
- Also, resulting from his visit to New York University, Kato's notes On the eigenfunctions of many-particle systems in quantum mechanics were published by the Mathematical Sciences research Institute of New York University in 1956.
- These notes extend results which were published in Kato's famous 1951 Transactions of the American Mathematical Society paper mentioned above.
- Although still based in Japan, Kato made many visits to the United States during the following years, visiting the National Bureau of Standards in 1955-56, and the University of California at Berkeley and the California Institute of technology in 1957-58.
- František Wolf at Berkeley had become interested in perturbation theory through Kato's work and played a major role in an effort which brought Kato to Berkeley in 1962 to become Professor of Mathematics.
- Kato had major difficulties in obtaining a visa for the United States because of the tuberculosis he had suffered.
- Let us mention a few more from Kato's great wealth of results.
- In 1983 he discovered the "Kato smoothing" effect while studying the initial-value problem associated with the Korteweg-de Vries equation, which was originally introduced to model the propagation of shallow water waves.
- Kato retired from his chair at Berkeley in 1988 but remained extremely active in research.
- However, Kato was willing to talk mathematics.
- Kato was an intensely private person who was deeply interested in nature and as a result he especially loved the Botanical Gardens at Berkeley, and he spent many happy hours there.

Born 25 August 1917, Kanuma City, Tochigi-ken, Japan. Died 2 October 1999, Oakland, California, USA.

View full biography at MacTutor

Origin Japan

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive