This news came as a great shock to me. Not only was Avner my host when I was a postdoc at Toronto, but also a good friend.
My first encounter with Avner was when I was interviewing for a postdoc position at Toronto. We got along really well, even though our primary research areas were quite different. After my interview talk came a question from Avner, trying to relate my work to a concept which I'd vaguely heard about, but never thought about deeply. It was an idea from "left field" - perfectly symptomatic of Avner's personality, as I later came to discover. Later, in Avner's office, he tried to explain his work to me. He was passionate, he was engaged, he was eloquent, and I understood: nothing! It was not that he wasn't a good communicator, it was more that he was a deeply original thinker, and he must have found it hard to understand why others didn't think the same way. Indeed this phenomenon kept recurring in later research conversations with him: I was never quite sure that I understood what he was saying, yet there was always food for thought...
During that short visit, I already had an inkling of Avner's offbeat personality, as well as of his warmth. I remember a pleasant evening spent in his home, with his family and their pet parakeet "Good Boy". The postdoc position didn't pan out, but Avner invited me for a visit at some future point of time, and I took up his offer a year and a half later. That was a fun time. I came to appreciate more what others have remarked upon: his unique sense of humour. His sense of humour wasn't merely verbal - it was expressed in tics of personality (the way he leant back in his chair, the quizzical smile), and in a manner that was always engaging and yet ironic. The occupant of the office opposite Avner's, Charlie Rackoff, has a strongly individualistic sense of humour himself, and they must have had some pretty interesting interactions over the years.
Subsequent to my visit, I ended up spending a year as a postdoc at Toronto, during which I got to know Avner even better. Among the things we had in common: vegetarianism, and a passion for the HBO show "Curb Your Enthusiasm" (CYE). I was a huge CYE fan, but my passion for the show paled in comparison to Avner's. He was perennially riffing on the protagonist Larry David, and my fellow postdoc Iannis Tourlakis and I used to be invited to Avner's home to watch reruns of the show. One of the reasons Avner loved the show, I suspect, is that it finds potential for comedy in the most ordinary everyday situations. Avner was like that: he abhorred dullness and routine, and was always looking for what was fresh and interesting about life. Josh mentions in his tribute Avner's aversion to cliche. The example I remember most vividly is his crusade against the phrase "as different as apples and oranges", on the grounds that they were much more similar than different - both round, both types of fruit etc.
I stayed in touch with Avner after I left Toronto, and got a chance to meet up with him again December of last year in Kanpur - we were both there for the FSTTCS conference. I helped him with the details of his train bookings from Delhi to Kanpur and back, and I found myself sharing a compartment with him and his son Roy. I'd invited Avner to come and visit me in Chennai, but Avner being Avner, what he was really looking forward to about the trip was the Himalayan trek with Roy following the conference. And Roy seemed just as enthusiastic about the trip, if not more. It was wonderful watching father and son together, the son clearly idolising the father.
There was a dinnertime conversation during the conference which will always remain in my mind for its buoyant, unpredictable quality. At one point, it emerged that our families both had dogs who had been obtained at the same time and were of approximately the same age. We joked that they should get to know each other over Skype. He asked me the name of our dog; when I told him, he said, "Yeah, I used to know a dog of that name". Then he thought about it a little bit. "I'm confused, that wasn't a dog, it was a friend." He pondered some more - turned out it was a dog after all! By this time I was laughing uncontrollably.
The conversation continued as we made our way back to our rooms - we discussed our latest comedic discoveries. I recommended "The Sarah Silverman Show" and "Flight of the Conchords"; Avner talked up a Canadian radio show called "Wiretap". "Wiretap" - I didn't think I'd ever heard of that... Avner flared up in mock outrage, he claimed he'd mentioned it to me in a recent e-mail. And indeed when I returned to my room, there was a new e-mail from him forwarding the previous one and saying "Shame on you Rahul for not checking the links I send you!!"
I will listen to Wiretap now, but it won't be funny, it will be poignant.