Grigory Perelman, the reclusive Russian mathematician who may have proved the elusive Poincaré Conjecture, was awarded with a 2006 Fields Medal at the International Congress of Mathematicians--and he turned it down, according to Nature.

Three other mathematicians--Princeton University's Andre Okounkov, UCLA's Terence Tao, and Wendelin Werner from France's University of Paris-Sud--were honored with this year's Fields Medal, considered by many to be mathematics' equivalent of the Nobel Prize. All three of them were present at the ceremony in Madrid to accept their awards.

According to the International Mathematical Union, a Fields Medal has never been turned down before.

Perelman, who reportedly lives with his mother in St. Petersburg, will be eligible for a $1 million Millennium Prize from the Clay Mathematics Institute if he is indeed determined to have proved the Poincaré Conjecture, a seemingly simple problem dealing with three-dimensional spheres. No word as to whether or not he 'll accept that one.

I wonder if he gave a reason for turning it down.

he said that he said everything significant in his publications and had nothing significant to say in public.

http://www.cnn.com/2006/TECH/science/08/22...s.ap/index.html

....proved a theorem about the nature of multidimensional space....the riddle Perelman tackled is called the Poincare conjecture, which essentially says that in three dimensions, a doughnut shape cannot be transformed into a sphere without ripping it, although any shape without a hole can be stretched or shrunk into a sphere.

That seems obvious on inspection. Why does it need proving?

This particular proof is quite involved. If it was obvious, it would have been proved a long time ago; $1 million wouldn't be offered for it either.