The world knows John as one of the inventors of collaborative filtering (go watch the re-presentation of the original GroupLens paper he wrote with Paul Resnick and others) and a leader in the field of recommender systems, as well as an influential researcher in social computing systems broadly.
For me, he is the one who taught me how to stay sane in the oft-insane world of academia.
I met John when I was assigned to be his TA for CS2 my first semester as a Ph.D student. Two things quickly stood out about him: 1, that he knew how to run an efficient meeting, and 2, that his family was a high priority. Throughout the semester I also saw him to be an excellent and thoughtful teacher.
The next summer, I was looking for summer funding, and he had some research funding for me. I didn’t leave GroupLens after that.
John didn’t demand bizarre hours or interminable work. He expected good work and productive research, and he modeled it. He also modeled a healthy balance of that work with fun and family. You work hard, you write the paper, you get some rest. You take time to exercise and stay healthy, be it playing squash, bicycling, or however you keep your body from falling apart. You take some time to play League of Legends. You make sure you’re there for your family. You study hard, work hard, and live hard. That is how he taught his students to live; that is the life that he lived.
I knew in theory that work shouldn’t come at the expense of my family, but you know what they say about theory and practice. John showed me a worked example of a life lived fully, of a thriving research and teaching career combined with a strong family.
He listened and looked to understand what each person he worked with needed. When I’ve come to his office frustrated with my research, he’s listened and helped me find the next step forward. As I have seen him interact with all of us around the lab, and heard stories of his influence, he was good at knowing what kind of push, motivation, or caring ear each of his students needed to carry on and move forward.
He didn’t impose a template for life on his students. I’ve always felt that he wanted to work with me to figure out what I wanted to do with my life and help me get there.
He was always kind and gentle. He provided thoughtful critiques.
He taught me to think like a scientist. To look for ways to test what is true. To think about what kind of experiment or data might test a claim or tease out the explanation of some interesting (or mundane) phenomenon.
I’m now headed into (hopefully) my last year of Ph.D studies. And a job search. I feel a bit like Rocky, training for the big fight, but Apollo’s dead. He won’t be in my corner any more. (If I carry this analogy too far, I’d be packing my bags for a Siberian vacation to retrain as a cancer researcher. I don’t think Jennifer would be very happy relocating to Siberia, but who knows, data mining for cancer diagnosis or treatment might be in my research future.)
Goodbye, John. I will miss you. Yours was a life worthy of emulation in so many ways; I can only hope that I have been half as good a student as you have been a teacher.