On Friday 25 January 2008, Fred Lunnon wrote:
You might have hoped you'd heard the last of this topic. However, a discussion with David Gale has inspired the following vicious conundrum.
Consider a transparent sheet of overhead projector film, onto which has been glued the legend "P A B L / N H Ã O" in plastic symbols, coloured green on the front and red on the back [from a numerate classicist toddler's alphabet: there would have been 10 symbols, but the swastika's been eaten]. ... Then begin again, but instead lay it against a mirror. The image again occupies the same space (more or less) as the original. The legend in the reflected image is legible and coloured red [or if you foozled it, illegible and coloured green --- whichever]. Question: is the reflected orientation positive, or is it negative?
I don't understand what the problem is. It's negative; the sheet is a three-dimensional object, even though one dimension is rather small, and you've reflected it across that small dimension. What's conundral about this? I'm obviously missing a subtlety... -- g