I have worked with David for almost a quarter of a century. He is a close friend, confidant, colleague and teacher. David has a rare combination of attributes: he is magnanimous, unpretentious, tenacious and, as anyone who has worked with him or knows of his work would add, brilliant. Nevertheless, David makes up for being smart by working extra hard. Let me share a few stories with you.
Marshall Buck, David and I have collaborated on a number of projects. We work so closely together that we actually write programs as an ensemble. One of us drives, usually David, and the other two kibitz. When we come to a stopping point, for example, if we’ve just finished a piece of code or finished discussing an idea, Marshall and I are ready for a break, but not David; he just keeps on going. In fact, he is quite a taskmaster. Not only that, David takes on any piece of a project, no matter how menial, if it’s needed to complete the project.
I also recall going out to dinner one Saturday night many years ago with David and Deborah. After dinner, we came back and were sitting in his living room when David announced that he was going upstairs to do math now. I guess that meant it was time to go home.
We also held Putnam lunches. To remind you, the Putnam exam is given every year to aspiring undergraduate mathematicians across the country. Marshall and David decided to start with the first Putnam exam and solve every problem up to the present. And so our lunches at restaurants ended up with place mats substituting for blackboards, homework assignments for the more difficult problems, and the following day, reports on the previous assignments. Putnam lunches grew in popularity and many other staff members joined in.
David even works hard at play. I remember one winter when the Goldschmidts, the Robbinses and my family went to a resort in the Catskills for a few days. David, although relatively new to skiing, hit the slopes like a banshee, just as he attacks a new problem at work.
When I first heard David lecture, I was impressed by the clarity, ease, and apparent effortlessness of his style. Well, as I learned later, he has a SECRET TRICK: he works hard to prepare. As many of you know David taught high school at Exeter, and David once told me that teaching was the hardest he had ever worked. That just shows how seriously David takes preparing a lecture.
This carries over to his writing as well. David’s papers are shining examples of exposition. On one of my first collaborations with David, we each wrote a section of the paper. I learned how high David’s standards are when he rewrote my section.
One of the best things about David is that he works from first principles. He takes nothing for granted. He has to understand everything. This is why his lectures are understandable, his papers are clear and working with him is so enjoyable and rewarding. He is also a very patient teacher.
When someone new at CCR asks for advice on which project to choose, I always say, “try to work with David Robbins, it doesn’t matter what the project is”. Everyone views working with David as a real treat.
After a lecture, David has been known to say, “I didn’t understand a word”. I learned that really means “I didn’t understand everything”. He has to understand everything or he is dissatisfied. I have a little story about that. Once, a long time ago, David got a letter from the IRS asking for more money, and as usual David said he did not understand a word. (Given that it was from the IRS, I guess he was accurate this time.) So David wrote back, saying he did not understand their letter. The IRS responded, and after a few iterations of the same, David came in one day and announced success: the IRS finally attached itself to David’s bank account. David said it was great. They don’t bother him any more, sometimes they take money out and sometimes they even put some back in.
David has an interesting, sometime playful, view on life, as the previous story illustrates. Here is another anecdote: David and Deborah were going to France for a month, and David used this as an opportunity to speculate on the EURO. He picked a fly-by-night company on the Internet, sent them some money, and I think in the end he actually made a few bucks.
On a personal note, a long time ago, I was in the hospital in Philadelphia, it was snowing and I needed some critical medical records from Princeton. And, as I will never forget, David braved the snow to bring them to me. We watched each other’s children grow up, shared experiences with parenting and gave each other advice. My children think quite highly of David. While my son was in high school, David tutored him and his friend for a math course they were taking at the University. And once, when my daughter was quite young, we were watching a Woody Allen movie and she remarked, “There’s David Robbins”.
As should be obvious by now, I have a lot of affection for David and consider myself fortunate to be his friend and colleague.