ESU5 Day 2

The second day of the conference started with a talk by Ulrich Rebstock titled "Mathematics in the service of the Islamic community". I must admit that my knowledge of Islamic mathematics is even worse than my knowledge of for instance European mathematics, and every talk on the subject is therefore sure to give me new information. Rebstock showed how much of Arab mathematics focused on practical aspects of mathematics, and gave examples from a wealth of books on subjects like measuring, taxes and trade. But the more "theoretical" mathematics was never far from the surface, for instance, examples with made-up "practical interest" were many. I particularly liked this example: In a Turkish bath, one day 30 visitors had payed their entrance. The owner knew there had been three Jews, and that he had collected 30 dirhams. The prices were Muslims 1/2 dirham, Christians 2 dirhams, Jews 3 dirhams... Another interesting example of mathematics of the time were inheritance problems when the gender of one of the beneficiaries were uncertain (!)

Thereafter, I joined Chris Weeks´ talk on Condorcet´s paradox. Condorcet wrote a treatise (Essai sur l´application de l´analyse a la probabilité des décisions rendues a la pluralité des voix) on the problem of voting, showing that any voting systems has its problems (although it should be possible to create a voting system that doesn´t repeatedly elect Bush president...) The treatise is very interesting, and it is tempting to use it with my students this autumn - especially as there is a local election coming up.

Then there was lunch. 99 crowns for a three-course meal is great - maybe a fifth of what I would expect to pay in Norway...