of the schoolgirls comes into its own.
It is called cyclic since on each subsequent day the walking schedule is
changed from a to b, b to c, down to g to a. The same applies to the upper-case
girls A to B, B toC, and so on, but Victoria remains unmoved.
The underlying reason for the choice of notation is that the rows correspond
to lines in the Fano geometry (see page 115). Kirkman’s problem isn’t only a
parlour game but one that’s part of mainstream mathematics.