First, what do we know about this puzzle? - There are 5*7*8*11 = 3080 possible positions. - Moves do not affect each other, so if you have a good set of moves, you can do them in any order. - There must be at least one move of the 8 ring, but not necessarily any of the others. Given this, it is a relatively simple algorithm to find the shortest sequence of moves. What I did was to start with a list containing only (0,0,0,0), then for each item in that list, I did a +5,-5,+7,-7,+8,-8,+11,-11. For each item produced by this, I check if it is in the list and if not, add it to the end. I had it stop when it got to (3,3,3,3). (0,0,0,0) -> +5<br> (1,2,2,2) -> +7<br> (4,3,4,4) -> -8<br> (1,5,3,2) -> -8<br> (3,0,2,0) -> -8<br> (0,2,1,9) -> -8<br> (2,4,0,7) -> -8<br> (4,6,7,5) -> -11<br> (1,1,1,4) -> -11<br> (3,3,3,3) So the minimum number of moves is 9. One example is(just reversing my list):<br> **+11,+11,+8,+8,+8,+8,+8,-7,-5** **Update:**<br> The maximum distance from any position to any other position is 14. Here is a list of the distances and the number of points for each distance. This is done from (0,0,0,0), but it holds for any point. 0: 1<br> 1: 8<br> 2: 32<br> 3: 84<br> 4: 168<br> 5: 284<br> 6: 420<br> 7: 397<br> 8: 344<br> 9: 330<br> 10: 324<br> 11: 324<br> 12: 250<br> 13: 100<br> 14: 14<br> An example of an item that is 14 moves from (0,0,0,0) is (3,1,5,1), which happens to be the last item in my sequence. The closest items with 3 0's are (0,0,0,3) and (0,0,0,8), which are 5 moves away.<br> The closest items with 3 0's and a 1 are (1,0,0,0) and (0,0,1,0), which are 7 moves away.<br> The furthest item with 3 0's and a 1 is (0,1,0,0) which is 12 moves away.<br> (0,0,0,1) is 8 moves away (to complete the set). **Update 2:**<br> The question was asked how I knew the 8 ring must move at least once, but not necessarily any of the others. There are two different parts to this. First, if you never move the 8 ring, moving other rings always causes it to move 2, which means it can only ever be at 1, 3, 5 or 7. So you must move it at least once to get it to an even number. Second, to never move another ring: I expected this to be true because all the ring sizes are relatively prime to each other (and to the moves, except for the 2-move and 8-ring), so if I move the 8 ring 3080 times, I should go through every permutation. If I move any other ring 1540 times, I'll go through half the permutations (because in that case, the 8 ring only stays on odd numbers). To verify this, I put together a quick spreadsheet to simulate moving each ring +1 3080 times. The spreadsheet showed this to be correct. It also showed that you can get to (0,0,0,0) by moving the 8 ring -1 only 51 times.