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Dr. Ecco Solution

Solution to "Calculation in the Narrows," DDJ, October 2005.

1. The configuration 5220 5220 5220 5221 5220 5220 5220 5219 5220 5220 5220 5220 5220 never changes because the 5221 never encounters 5219 and all rounding is to the nearest whole number where the initially higher number rounds up. If the number acquiring the higher number were chosen at random, then this would converge.
2. The following configuration requires 38 rounds when using one decimal point: 1287 6733 7176 4061 9928 797 8570 82 9642 287 7823 823.
3. The following initial configuration requires 14 rounds 0 0 10000.
4. Every configuration completes in finite time, because eventually (with probability 1), if two numbers differ by two or more, two people having those numbers will eventually meet.

DDJ