(I'll return to continued fractions in a moment.) The sign diagram is actually an oversimplification: The five lanes empty into eight+ perpendicular ones, two of which have immediate "Must turn left" and "Must exit" consequences. On top of all this, there are one or two panhandlers at the five-cross-eight light, and idiots stopping to give them money. What will it take to give a GPS a nervous breakdown? Anyway, this intersection is near Neil's. The ARCO nearest Neil's has five pumps in a quincunx, each protected by heavy steel pipes enclosing a LARGE "Please pull forward" sign. (Oh why didn't I think to take a photo?) People coming to a pair of pumps from opposite directions are thus requested to pull into each other. Perhaps in recognition of this, four of the signs have been covered with LARGE cardboards reading "Welcome to the intersection of low prices and good value". Leaving only the middle pump to read "Please pull forward", to where there is no pump. --rwg On Tue, Dec 4, 2012 at 5:52 PM, Bill Gosper <billgosper@gmail.com> wrote:

You know those black and white traffic signs at stoplights that say, e.g., "U Turn from left lane only" only the only text is "ONLY" and the rest is various arrows? Can you top this<http://gosper.org/arrows.JPG>? California has legalized driverless cars. As a step toward mandating them. --rwg