12/01/2018

Folha: Pál Erdös, for whom mathematics was life.

The Hungarian mathematician Pál Erdös (pronounced 'Erdech') visited Brazil only once, in 1994, at the invitation of Professor Yoshiharu Kohayakawa of the University of São Paulo. By then, he was already a living legend. The stay was typical of the eccentric way he chose to live his life.

He visited several institutions, including IMPA (Institute for Pure and Applied Mathematics), interacting with colleagues and students. By the end, he already had a collaborative research project with Yoshiharu and another colleague.

Erdős was born in Budapest in 1913, the third and last child of a Jewish couple who were mathematics professors. His two sisters died of scarlet fever a few days before his birth. His father was a prisoner of war in Siberia from 1914 to 1920.

Those hard years, struggling to survive, forged an extraordinary bond between mother and son. Erdös never married, never had formal employment, and never settled down. He spent his life traveling the world, with the help of colleagues and friends, with all his belongings contained in two suitcases: one with clothes, the other with mathematical work. His mother accompanied him throughout his life.

In terms of the number of written works, he is the most prolific mathematician in history: 1,525, almost all in collaboration with others. Friends honored his intellectual generosity and pleasure in collaborating by inventing the concept of "Erdös number".

Those who co-authored research papers directly with him, like Yoshiharu, have the number 1. There are 511 of them. My colleague Gugu, from IMPA, has published works with Yoshiharu and therefore has an Erdős number of 2. There are more than 11,000. I have articles with Gugu, so I have the number 3. But there are so many of us that nobody bothers to count! Recent research with 400,000 mathematicians showed that the highest Erdős number is 13.

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