was a Japanese mathematician who worked in the field of functional analysis. He is known for the Hille-Yosida theorem concerning C0-semigroups. Yosida studied mathematics at the University of Tokyo, and held posts at Osaka and Nagoya Universities. In 1955, Yosida returned to the University of Tokyo. See also Einar Carl Hille Functional analysis References Kôsaku Yosida: Functional analysis. Grundlehren der mathematischen Wissenschaften 123, Springer-Verlag, 1971 (3rd ed.), 1974 (4th ed.), 1978 (5th ed.), 1980 (6th ed.) External links Photo Kosaku Yosida / School of Mathematics and Statistics University of St Andrews, Scotland 94. Normed Rings and Spectral Theorems, II. By Kôsaku YOSIDA. Mathematical Inlstitute, Nagoya Imperial University. (Comm. by T.TAKAGMI, M.I.A. Oct.12,1943.) Kosaku Yosida (1909 - 1990) - Biography - MacTutor 1909 births 1990 deaths 20th-century Japanese mathematicians Mathematical analysts Functional analysts Operator theorists Approximation theorists University of Tokyo alumni Academic staff of the University of Tokyo Academic staff of Osaka University Academic staff of Nagoya University Laureates of the Imperial Prize