and I can’t help but remember him.
I first met Sam as an undergraduate at Caltech where he was TA for Hopfield‘s class, and again when I visited Gatsby, when he invited me to visit Toronto, and at too many conferences to recount. His personality was a combination of enthusiastic and thoughtful, with a great ability to phrase a problem so it’s solution must be understood. With respect to my own work, Sam was the one who advised me to make my first tutorial, leading to others, and to other things, all of which I’m grateful to him for. In fact, my every interaction with Sam was positive, and that was his way.
His death is being called a suicide which is so incompatible with my understanding of Sam that it strains my credibility. But we know that his many responsibilities were great, and it is well understood that basically all sane researchers have legions of inner doubts. Having been depressed now and then myself, it’s helpful to understand at least intellectually that the true darkness of the now is overestimated, and that you have more friends than you think. Sam was one of mine, and I’ll miss him.
My last interaction with Sam, last week, was discussing a new research direction that interested him, optimizing the cost of acquiring feature information in the learning algorithm. This problem is endemic to real-world applications, and has been studied to some extent elsewhere, but I expect that in our unwritten future history, we’ll discover that further study of this problem is more helpful than almost anyone realizes. The reply that I owed him feels heavy, and an incompleteness is hanging. For his wife and children it is surely so incomparably greater that I lack words.