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Trip report E.W. Dijkstra, Han-sur-Lesse, 7-12 Jan. 1981.

Compared with the size of the globe, the distance between Neunen and Han-sur-Lesse is very short. But the meeting I attended was not worth travelling it. It was a meeting of IFIP WG2.3 "Programming Methodology", which was boring instead of exciting. (The most exciting part of it may have been the visit to the world-famous caves, but this poor tourist did not join the excursion.)

I greatly admired Tony Hoare's power of concentration --and envied him for it-- : whenever the "presentation" did not interest him, he just worked. Tony had a few productive days. The meeting improved 24 hours before its closure when Tony showed, on the blackboard, what he had been doing during the past days and was followed by Cliff Jones, who blew the lamp of the overhead projector. (Like a good Belgian --thank goodness!-- our host did not have a spare.)

These meetings have their problems: we have members willing to show results that might interest others or to introduce promising topics for discussion, but we also have members who would like to show what they have done. In earlier years, speakers from the latter category could be diverted, but that is much harder now. We

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are a bit too polite; besides that, how does one divert a presentator that clings for dear life to his foils --"prepared in advance"-- when they are the only thing he's got and he insists on completing the show? The foils are there, so he needs the feedback from the audience as little as a film projector needs it; hence, he can ignore his audience, and often does so. People that give presentations instead of lectures should be accused of the offence of "contempt of audience".

My shortest explanation of the sorry state of American computing science is the observation that the topic still had to become of age after the overhead projector had taken over the American University Campus. Last week has strongly confirmed my opinion that the wholesale defenestration of overhead projectors would be a most salutary measure. (The argument that "preparation in advance" improves the quality of the way of presentation hardly seems to hold water: almost all we were shown was ridiculous. The foils of Parnas were geared to the illiterate manager --you know the type of foil: "capitals only" was one of its leading characteristics-- ; in honour of his wonderful printing equipment, Balzer had used seven different type fonts on a single foil and, besides that, he spelled "auxiliary" as he pronounced it: "auxillary"; most of the others

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switched from colour to colour with neither rhyme nor reason: in Horning's case the colour of his printed foils was determined by the whims of his secretary.)

To my taste too many speakers identified the problems of computing science with the difficulty of computing in an illiterate environment.

In a discussion about the effectiveness of mathematical arguments I showed for comparison two different proofs of the same theorem: a usual one and a beautiful one. Afterwards Parnas suggested that I had shown the latter mainly to boost my ego. Apart from that remark (which I think pitiable), the meeting was quite good-humoured and often very funny. (Sometimes it was even too much so; controversy has been laughed off and I fear that the exchange of scientific ideas has been hampered.)

Three cheers for our host Michel Sintzoff! Our accommodation was perfect. Travel to and from the place was a little bit difficult, "but the food was excellent".

Plataanstraat 5
The Netherlands
13 January 1981
prof.dr. Edsger W. Dijkstra
Burroughs Research Fellow

Transcription by John C Gordon

Last revised on Mon, 30 Jun 2003.