Trip Report Visit ETH Zurich, 3–4 February 1975 by E. W. Dijkstra

Invited by Niklaus Wirth I gave three lectures at the Eidgenossische Technische Hochschule Zurich. The first one (Monday 16.00–18.00) was reasonably successful, the second one (Tuesday 11.00–12.00) was bad —at the end I lost my way in a trivial proof and had to give up—, the last one (Tuesday 14.15–16.00) went perfectly. For some reason I was very tense. For instance, I completely forgot to open each lecture (as usual) with a quotation! I also forgot the first day to invite “interrupting questions”. Niklaus suggested that at my second talk I should give the audience some “homework” for the break at lunch. I did so, but at the beginning of the second talk instead of at its end: one question was so intriguing that more than one member of the audience tried to solve the problem during the lecture.