To the Memory of Alexander Grothendieck: a Great and Mysterious Genius   of Mathematics
  In November 2014 Alexander Grothendieck passed away at the age of 86. There is no doubt that he was one of the greatest and most innovative mathematicians of the 20th century. After a bitter childhood, his meteoric ascent started in the Cartan Seminar in Paris, it led to a breakthrough while he worked in Sao Paulo, and to the Fields Medal. He introduced numerous new concepts and techniques, which were involved in the groundbreaking solutions to long-standing problems. However, dramatic changes were still ahead of him. In recent years hardly anybody knew where he was living, and even if he was still alive; he had withdrawn to a modest life in isolation. Also beyond his achievements in mathematics, Grothendieck was an extraordinary person. This is a tribute of his fascinating life. 
Wolfgang Bietenholz and Tatiana Peixoto
math.HO