An anonymous reader writes Alexander Grothendieck, one of the great eccentric geniuses of 20th century mathematics, has died in France at the age of 86. Grothendieck was the leading mind behind algebraic geometry. He was awarded the Fields Medal in 1966. He reached the very pinnacle of his profession before abandoning the discipline, taking up anti-war activism, retreating into the life of a recluse and refusing to share his research. He died on Thursday in a hospital in Saint-Girons in southwestern France.