A Farewell to Ricky Pollack

Abstract

How are you, Ricky? Until the very end, whenever I called him, he answered on the most cheerful note: Wonderful! This was not simply a mannerism on his part. It was enough to meet Ricky once to realize that he was an incorrigible optimist. What was the source of his optimism? After almost 40 years, I have some clues, but no satisfactory answer. Ricky did not have an easy start as a mathematician. When his uncle found out about his academic ambitions, his first reaction was: Are you nuts? How much money does a professor make? I can hire half a dozen people at such salaries! Start a business! But Ricky had no interest in money. His parents and many of their friends were Communists. During the McCarthy era, they were harassed by the authorities because of their political views. Ricky was one of the "red diaper babies." He shared his parents' dreams and wanted to make a difference. He always liked puzzles and chess, he excelled in mathematics, and above all he loved people. To become a teacher or a professor seemed like a natural goal for him. He was accepted to the PhD program in mathematics at NYU and started to do research in number theory under the direction of Harold N. Shapiro. After defending his thesis, he joined NYU as a professor. It must have been difficult for him to stay so close to his thesis advisor, who was not only a brilliant mathematician and engaging educator, but also had an imposing personality. It was the golden era of analytic number theory, and the field was full of extraordinary talents. It required a die-hard optimist like Ricky not to be discouraged by the grandeur of their achievements and to continue to do research. After spending a sabbatical in Montreal with Willy Moser and reuniting with his intellectual twin brother, Eli Goodman, he switched direction: the two of them started a lifelong collaboration in combinatorial geometry. The rest is history. In an effort to understand and improve the Erdős-Szekeres theorem on convex polygons and to give a combinatorial description of other geometric configurations, they explored the notion of allowable sequences, which has become a János Pach