Trailblazing mathematician Paul Cohen, who developed a technique known as forcing to test a hypothesis, has died in Stanford, Calif., at the age of 72.

Family members told The New York Times Cohen died March 23 of lung disease.

In the 1960s as a professor at Stanford University, he took up the challenge of set theory from the 19th century, and developed the continuum hypothesis, the question involved in establishing the sizes of infinite sets of real numbers, the report said.

As a result, Cohen received the Fields Medal for outstanding achievement from the International Mathematical Union in 1966.

Peter Sarnak, a former student of Cohen's who is a professor of mathematics at Princeton, told the Times Cohen "introduced techniques that will probably allow us to solve many other things, opening a floodgate of mathematical activity."

Cohen is survived by his wife, three sons, a sister and brother.

*Copyright 2007 by United Press International*

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