Joel Hass
Joel Hass is an American mathematician, a professor of mathematics and chair of the mathematics department at the University of California, Davis.Biography
Hass received his Ph.D. from the University of California, Berkeley in 1981 under the supervision of Robion Kirby. He joined the Davis faculty in 1988.
In 2012 he became a fellow of the American Mathematical Society.Hass is known for proving the equal-volume special case of the double bubble conjecture, for proving that the unknotting problem is in NP, and for giving an exponential bound on the number of Reidemeister moves needed to reduce the unknot to a circle.;Research papers
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