History and Context for Defining Liveness: Winner 2018 Edsger W. Dijkstra Prize

It's great to be back at PODC. I attended this conference religiously through 1992. It's interesting to see what has changed but also what has not changed in 25 years. And I can't think of a happier excuse to be back. All of us know how gratifying it is to see that our work is having impact, and that's what this award signi es. To win an award that carries Dijkstra's name is especially meaningful for me. As a graduate student, I read and reread Dijkstra's work; it changed the way I looked at systems research and the research enterprise. (Bowen will o er some remarks that expand on this theme.) I then had a chance to meet Dijkstra when I served as teaching assistant for a 1-week short course he taught in Santa Cruz. That was the summer following my rst year as an assistant professor at Cornell; my colleague David Gries had gotten me the assistantship. I guess I did OK, because Dijkstra and his wife Ria subsequently invited me to visit their home in Nuenen (The Netherlands) for a week. What a thrill. I subsequently saw Dijkstra at technical meetings and socially at least once a year, until he passed away. So, yes, I have many Dijkstra stories to tell. Catch me after dessert for those. You can read our paper \De ning Liveness" (it's only 5 pages!) if you are interested in the technical details. I thought that instead I would talk about how we developed those ideas and where things stand today. I'm always fascinated by the history behind discoveries, and I suspect that I'm not alone in enjoying this \academic gossip".