Joel Hass

Joel Hass is an American mathematician and a professor of mathematics and at the University of California, Davis.

Hass received his Ph.D. from the University of California, Berkeley in 1981 under the supervision of Robion Kirby.

[3] From 2010 to 2014 he served as the chair of the UC Davis mathematics department.

[4] Hass is known for proving the equal-volume special case of the double bubble conjecture,[5] for proving that the unknotting problem is in NP,[6] and for giving an exponential bound on the number of Reidemeister moves needed to reduce the unknot to a circle.

[7] 2004: Student Solutions Manual, Maurice D. Weir, Joel Hass, George B. Thomas, Frank R Giordano