Hi Jeff You wrote: Detecting cycles will involve a lot of bikeshedding. (Sorry, couldn't

resist.)

Indeed. That really brought a smile to my face. Thank you. As I recall, bikeshedding is endless discussion (cycles again) of the COLOUR to paint the bikeshed. And in mathematics there's the topic of https://en.wikipedia.org/wiki/Graph_coloring. By the way, according to wikipedia, the convention of using colors originates from the coloring of the countries of a map, as in the famous https://en.wikipedia.org/wiki/Four_color_theorem. Once again, thank you for your careful attention and sense of humour. -- Jonathan