the man who loved numbers (8) poor great old man

In the early 1970s, Erdös appended the PGOM to his name, which Poor Great Old Man. When he turned 60, he became PGOMLD, the LD for Living Dead. At 65, he graduated to PGOMLDAD, the AD for Archaeological Discovery. At 70, he became PGOMLDADLD, the LD for Legally Dead. And, at 75, he was PGOMLDADLDCD, the CD for Counts Dead (he explained that after the age of 75 you count as a member of the Hungarian Academy of Sciences).

When Paul Turan, his closest friend, with whom he had written 30 papers, died in 1976, Erdös had an image of the SF the work he had done with collaborators.

On one side of a balance, the SF would place the papers Erdös had co-authored with the dead; on the other side, the papers written with the living. "When the dead side the balance," said Erdös, "I must die too." He paused for a moment and then added: "It's just a joke of mine."

Perhaps. But for decades Erdös vigorously sought out new, young collaborators and ended many working sessions with the : "We'll continue tomorrow if I live."

With 485 co-authors, Erdös collaborated with more people than any other mathematician in history. Those lucky 485 to have an Erdös number of one, a code phrase in the mathematics world for having written a paper with the master himself.

If your Erdös number is two, it means you have published with someone who has published with Erdös. If your Erdös number is three, you have published with someone who has published with someone who has published with Erdös. Einstein had an Erdös number of two.

"I was told several years ago that my Erdös number was seven," one mathematician wrote in 1969. "But it has been lowered to three.

"Last year I saw Erdös in London... When I told him the good news that my Erdös number had just been lowered, he regret that he had to leave London that day. , an ultimate lowering have been ."