wilmott.com

I was flicking through a book where I was visiting at the weekend, and I came across the problem of Turing Bicycle. Can't remember exactly what it was, but it went something along the lines of this:If a single sprocket on the bike's gears was bent it would cause the chain to break... it then went on to discuss the different states the bike could be put into that would mean (a) the bike would breakdown so no-one could steal it (b) Turing could ride all the way home.I did a quick google for the problem and could not find it. Anyone want to enlighten me?

The book is "Cryptonomicon", by Neal Stephenson. The Turing Bicycle problem relates two numbers (related to the gears/chains/sprockets of the bycicle), and uses them to help the reader understand the the notion of using a periodic substitution for coding. If both numbers were relatively prime the distance the bicycle would travel would be longer. Adding a fourth wheel to an Enigma machine would increase the period of the code. The whole book is worth reading.

Ahh - thats the fella - serves me right for looking at peoples book cases when they are getting ready to go out!! I will read (as per my other posts another s*ding book to add!).

Hodges well-known biography of Turing mentions that his bicycle developed a fault which periodically caused the chain to come off but rather than getting it fixed he determined the periodicity and was able to prevent it by some unspecified means. Presumably this involved getting off and manually getting the chain past the critical point.

Dear Hermit rmax:I know only "Tuning Machine" in this sort of kind.(I have had been thinking that it is a spelling mistake.)How miserable I am! TooNeat, Les Miserable