Choice numbersIssue 3
This letter appeared in The Independent and is reprinted with their kind permission.
So, Peter Todd has told the British Psychological Society that the best strategy for finding a life partner is to examine a dozen, and then make a choice from those who come along later (report, 5 April).
Plus ça change! For 30 years, undergraduate students studying dynamic programming, a branch of operational research, have looked at this problem as a light-hearted example of an important mathematical approach to making one decision after another. In various guises it has appeared in many examination papers, along with the problem of choosing the best pub for lunch (try two or three depending on how far apart they are) and how to adopt a winning strategy at darts (which requires an honest assessment of how accurately you throw).
The same mathematics is in daily use for obtaining attractive layout of print in computerised typesetting around the world. This branch of mathematics does not tell us what to do if the potential life partner is adopting the same strategy and you are only number eight on his or her list. You will be rejected, automatically!
Dr David K Smith
University of Exeter