  The evolution equation for $q \bar q$ production introduced by Marchesini and
Mueller posed some intriguing mathematical puzzles, both numerical and
analytic. I give a detailed account of the numerical approach which led
eventually to the exact solution. While part of the work was in fact along a
wrong track, it turns out that some of the techniques involved are interesting
in their own and applicable to many other problems, i.e. to the numerical study
of Ricci flows.
