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Japanese-American mathematician (1928–2019) From Wikipedia, the free encyclopedia
Isaac Namioka (April 25, 1928 – September 25, 2019)[1] was a Japanese-American mathematician who worked in general topology and functional analysis. He was a professor emeritus of mathematics at the University of Washington.[2] He died at home in Seattle on September 25, 2019.[3]
Namioka was born in Tōno, not far from Namioka in the north of Honshu, Japan. When he was young his parents moved farther south, to Himeji.[4] He attended graduate school at the University of California, Berkeley, earning a doctorate in 1956 under the supervision of John L. Kelley.[5] As a graduate student, Namioka married Chinese-American mathematics student Lensey Namioka, later to become a well-known novelist who used Namioka's Japanese heritage in some of her novels.[4]
Namioka taught at Cornell University until 1963, when he moved to the University of Washington.[1] There he was the doctoral advisor to four students. He has over 20 academic descendants, largely through his student Joseph Rosenblatt, who became a professor at the University of Illinois at Urbana–Champaign.[5]
Namioka's book Linear Topological Spaces with Kelley has become a "standard text".[1] Although his doctoral work and this book both concerned general topology, his interests later shifted to functional analysis.[6]
With Asplund in 1967, Namioka gave one of the first complete proofs of the Ryll-Nardzewski fixed-point theorem.[7]
Following his 1974 paper "separate continuity and joint continuity", a Namioka space has come to mean a topological space X with the property that whenever Y is a compact space and function f from the Cartesian product of X and Y to Z is separately continuous in X and Y, there must exist a dense Gδ set within X whose Cartesian product with Y is a subset of the set of points of continuity of f.[8][9] The result of the 1974 paper, a proof of this property for a specific class of topological spaces, has come to be known as Namioka's theorem.[10]
In 1975, Namioka and Phelps established one side of the theorem that a space is an Asplund space if and only if its dual space has the Radon–Nikodým property. The other side was completed in 1978 by Stegall.[11]
A special issue of the Journal of Mathematical Analysis and Applications was dedicated to Namioka to honor his 80th birthday.[1] In 2012, he became one of the inaugural fellows of the American Mathematical Society.[12]
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