16 Aug
2009
16 Aug
'09
8:50 p.m.
For more on this puzzle, see http://oskarvandeventer.nl/M12/Developing_Topsy_Turvy_and_Number_Planet.doc.... Note that Oskar's "pachinko" mechanism (which can be seen on YouTube at http://www.youtube.com/watch?v=Yu3iZDKutCM) implements chip-firing in a lovely way. Jim