photo du jour

the "L" on all 6 faces with beautiful rotational symmetry

the “L” on all 6 faces with beautiful rotational symmetry

greetings all from a lovely village near Aix! i’ve seen many many lovely sights and been hosted by the marvelous Yvette and D here! But this has got to make highlight of the day: the “L” !! loong loong time ago during teenage years i spent days and weeks fiddling around with the rubik cube and found a very nice L-pattern with beautiful rotational-symmetry.. and for the last 20+ years unable to get anyone to dissect the move with, mainly because, as you can see from the video below, i can’t do it while looking 😀 . More importantly it took *six* forward rotational-symmetric moves to get there but only a combo of 3+1 (3 forward and 1 backward) rotational-symmetric moves to get back! and even more critical: there’s only a 10% chance to get back to 6-faces, other 90% i had to restart from scratch.. until this noon when i consistently (hence found a way) to get back.. In the past, every time i tried to sit down to try to understand, the continuous rotations made my head go dizzy…

debugging code

debugging code

that is until i demonstrated to the wonderfully knowledgeable D here, who promptly forwarded me the ENTIRE book on rubik cube, as well as conducted an analysis based on definition of moves, and voilà we now have a systematic language (generic formula) to get there and back from any orientation! The fact of the 3+1 offered an insight: first that you only need 4 instead of 6 moves, and that the +1 being a backward move is equal to 3 forward moves, hence the extra 3+3 forward vs 3+1 for+back! took us 1 day to ponder and 1 full evening for D to devise language and test, after i self-taped for demonstration! So, how’s that for solving a 20+year puzzle eh!