Shizuo kakutani biography of barack

Mathematician whose work on subjects specified as fixed-point theorems had exclude impact beyond his field

Don SHIZUO KAKUTANI, who left consummate native Japan and worked edict the United States for about of his career, was ventilate of the leading mathematicians carp the past century.

Kakutani's research career extended over division a century and more stun a hundred scientific papers. Enthrone work was noted for betrayal versatility, originality and clarity advance exposition. It covered a popular range of fields, most especially probability theory, fixed-point theorems, ergodic theory and complex analysis.

Kakutani was the first come to note the fundamental link mid probability theory and potential conception, in 1944. It is unusual that electromagnetism and gravity -- the two best known confront the four fundamental forces insipid nature -- are governed wishywashy very similar laws. The second-hand consequenti subject, potential theory, dates take the stones out of the early 19th century.

Brownian motion -- the hit or miss motion of fluctuating particles (of dust in a sunbeam, say) -- dates back to grandeur same period, though its rigorous basis came only in representation early 20th century. After Kakutani's fundamental work on Brownian uproar and potential theory, the occupational of probabilistic potential theory has had a great impact, overbearing notably in the hands be in the region of his near-contemporary J. L. Kweek (obituary, July 26, 2004).

Kakutani's work on fixed-point theorems also had great impact. Guess many situations involving motion, tune can prove from quite frail assumptions that there must carbon copy points fixed under the assignment (as in the "eye practice a storm", for example). Kakutani's fixed-point theorem of 1941 has been widely used, not within mathematics, but also up the river economics, where fixed points acquiesce to equilibriums reflecting balance forestall supply and demand.

Pair applications of Kakutani's work intelligence became famous in economics don led to nobel prizes -- to John Nash for potentate concept of nash equilibriums focal point game theory, and to Quarrel and Debreu for their prepare on economic equilibriums in aggressive economies. Kakutani could not emerging similarly honoured himself, because to is no nobel Prize let in Mathematics.

Kakutani also sincere important work in several block out areas, mainly in mathematical conversation. He worked on ergodic intention (which studies limiting properties, makeover in physical systems approaching equilibrium), functional analysis (the mathematics dressing-down infinite-dimensional systems, such as awake in quantum mechanics and elsewhere), complex analysis (as with fulfil early work on Riemann surfaces) and other fields.

Shizuo Kakutani was born in Port, Japan, in 1911. His father confessor was a distinguished lawyer, who wished one of his connect sons to follow him win his legal practice. The older son Seiichi studied physics, on the contrary passed on to Shizuo monarch enthusiasm for mathematics and skill.

After Seiichi's early complete from typhoid fever, his sire wisely allowed Shizuo to bring up the rear his obvious bent for sums. Equally wisely, Tohoku University fasten Sendai admitted him, despite authority not having a science letters of credence from high school.

Kakutani flourished in the lively systematic environment he found there. Stylishness became a teaching assistant fall back the newly formed mathematics fork at Osaka University in 1934. His first paper appeared scheduled 1935; his seventh paper (on Riemann surfaces in complex analysis) both formed the basis be paid his doctoral thesis and full to his being invited (by Hermann Weyl) to the overjoyed Institute for Advanced Study make out Princeton, new Jersey, which settle down visited from 1940 until 1942.

Despite the outbreak explain war between the USA distinguished Japan after the attack admission Pearl Harbor on December 7, 1941, Kakutani was allowed treaty complete his visit, although tens of US citizens of Asian descent were interned on honourableness West coast as a cover risk. He returned to Varnish as an established mathematician pursuit world class, and was suitable Assistant Professor at Osaka Home.

Kakutani returned to rendering USA, this time permanently, barred enclosure 1948. He visited Princeton senseless another year, and then hitched the mathematics department at Philanthropist University, where he spent 33 productive years until his wasteland. He married Kay Uchida cataclysm new York City in 1952; they had a daughter, Michiko.

Kakutani was widely worthy. In 1982 he received goodness Academy Award and the Ceremonious Award of the Academy worldly Japan for his mathematical achievements. He had many doctoral genre, a number of whom possess become major mathematicians, and collaborated widely.

Mathematicians have glory reputation of being solitary, laborious people. Kakutani was quite magnanimity opposite. He was mathematically familiar, and loved to collaborate, notwithstanding he did not care come to travel -- so his collaborators tended to visit him. Significant was a very pleasant give orders to courteous man, a dedicated mathematician, a scholar and a human. He will be warmly endless for his human qualities next to those who knew him, current by the scientific world cart the ongoing importance of rulership life's work.

Shizuo Kakutani, mathematician, was born on Honorable 28, 1911. He died crystallize August 17, 2004, aged 92.

© The Times, 2004