Remembering Paul Cohen (1934–2007) Peter Sarnak, Coordinating Editor
Remembering Paul Cohen (1934–2007) Peter Sarnak, Coordinating Editor Paul Joseph Cohen, one of the stars some classic texts. There he got his first exposure of twentieth-century mathematics, to modern mathematics, and it molded him as a passed away in March 2007 at the mathematician. He tried working with André Weil age of seventy-two. Blessed with a in number theory, but that didn’t pan out, and unique mathematical gift for solving instead he studied with Antoni Zygmund, writing difficult and central problems, he a thesis in Fourier series on the topic of sets of made fundamental breakthroughs uniqueness. In Chicago he formed many long- in a number of fields, the most spec- lasting friendships with some of his fellow stu- tacular being his resolution of Hil- dents (for example, John Thompson, who re- bert’s first problem—the continuum mained a lifelong close friend). hypothesis. The period after he graduated with a Ph.D. Like many of the mathematical gi- was very productive, and he enjoyed a series of Paul Cohen ants of the past, Paul did not restrict successes in his research. He solved a problem his attention to any one specialty. of Walter Rudin in group algebras, and soon To him mathematics was a unified subject that after that he obtained his first breakthrough on one could master broadly. He had a deep under- what was considered to be a very difficult prob- standing of most areas, and he taught advanced lem—the Littlewood conjecture. He gave the first courses in logic, analysis, differential equations, nontrivial lower bound for the L1 norm of trigo- algebra, topology, Lie theory, and number theory nometric polynomials on the circle whose Fourier on a regular basis.
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