5 ms·

Is there a category for robot solvers that have to fulfil the same requirements as a human solver? In other words, I'd like like to know how fast you can build

Is there a category for robot solvers that have to fulfil the same requirements as a human solver? In other words, I'd like like to know how fast you can build a robot that has to start with the cube lying on a table in front of it, and the manipulators (hands, in the human case of course) being away from the cube, with the timer stopping when the cube is back on the table and the manipulators are back in their original position?

aidenn0 9y ago
That would be interesting. Though this rule has a handicap that human solvers do not. They do not inspect the cube prior to starting the clock; unlike in human solves where they are given time to study the cube before the clock starts.
- lokedhs 9y ago
  That's a fair point, and it would make sense to allow the same for the robot. That could mean that you can allow for preprogramming the layout before. Or you could put two cameras on the robot to take pictures of 5 of the sides. I believe you can infer the last side based on knowledge of the others. In any case, given the fact that the human record for solving a cube is about 4.5 seconds, building a robot that can beat that would certainly be possible, but likely harder to do than the one from the article.
  - Someone 9y ago
    ”I believe you can infer the last side based on knowledge of the others.” Can you? If you flip all four edge pieces on the bottom face the bottom color shows up at all four side faces, and you wouldn’t be able to determine whether those four edge pieces got permuted, too.
    - TheSpiceIsLife 9y ago
      If you know the centre piece colours of five sides you know the remaining centre, the one you can’t see, must be the remaining colour.
      - 4ndr3vv 9y ago
        Quite. But we're talking about the permutation of the edge pieces on that face. You wouldn't be able to infer where they needed to be moved to if they were all just showing the bottom face colour.
        TheSpiceIsLife 9y ago
        Oh, I see. Yes, that's obviously what your comment was saying. Thank you for clearing that up.
    - lokedhs 9y ago
      Good point. I stand corrected. In retrospect, it was obvious enough that I should have thought of it.
    - Someone 9y ago
      Thinking a bit more about it, this problem already pops up if the bottom face has either: - three edge pieces that share a color, with that color showing on the side. - two pairs of edge pieces that share a color, with the twice shared colors showing on the side. The first isn’t uncommon; if you pick three edges at random, the probability that they share a color is 1 * 6/11 * 2/10 = 6/55, and there are four ways to pick three edges from the bottom face, for (I think) a total probability of 24/55 - 4 * 6/55 * 1/9 (the probability that all four share the same color), or a probability of over 1/3 (if that seems high, consider the following: because of the pigeonhole principle, between the edges of any face of the cube there always is at least a pair sharing a color). That means that, even ignoring the second possibility, there’s at least a 1:24 probability of seeing this problem on a random cube.
    - gweinberg 9y ago
      Not all cube configurations are achievable by cube moves. That is, if you pull off one corner of a cube, rotate it, and stick it on again you get a cube which cannot be solved (except by disassembling it again). I think it actually is possible to infer the sixth side of a cube if you can see the other 5, because only only one configuration of the remaining side is actually acheivable.
- otherme1 9y ago
  They say the machine spend about 50ms adquiring images and solving, and 335ms moving the cube.
gowld 9y ago
Picking up and putting down a cube from a known location, and visually analyzing it, are both solved problems. It's a boring and arbitrary restriction. One could just as well require the manipulators start 100 yards away, which would be biased toward fast-moving robots.
- TheSpiceIsLife 9y ago
  Similarly, building a robot that has shafts fixed to the cube’s centres is a solved problem. Quite boring indeed.
  - TheSpiceIsLife 9y ago
    Replying to myself to add: maybe we could see a triathlon with three stages of intellectual pursuit added to the three stages of physical activity. Run one hundred meters, solve a Rubik’s Cube, swim one hundred meters, solve a riddle, cycle five kilometres, then the first two who complete that have to head off in a game of Go. Why not? There’s people advocating eSports be included in the Olympics, so I’m open to anything at this stage.
    - Pamar 9y ago
      See also Chess Boxing: https://en.m.wikipedia.org/wiki/Chess_boxing https://en.m.wikipedia.org/wiki/Chess_boxing
      - TheSpiceIsLife 9y ago
        Amazing! Thank you! I'd not seen this before.
      - kgwgk 9y ago
        And Turing’s “round-the-house” chess: after you move, run around the house, if you get back before your opponent's move you are entitled to a new move.
- phkahler 9y ago

aidenn0 9y ago

That would be interesting. Though this rule has a handicap that human solvers do not. They do not inspect the cube prior to starting the clock; unlike in human solves where they are given time to study the cube before the clock starts.

lokedhs 9y ago
That's a fair point, and it would make sense to allow the same for the robot. That could mean that you can allow for preprogramming the layout before. Or you could put two cameras on the robot to take pictures of 5 of the sides. I believe you can infer the last side based on knowledge of the others. In any case, given the fact that the human record for solving a cube is about 4.5 seconds, building a robot that can beat that would certainly be possible, but likely harder to do than the one from the article.
- Someone 9y ago
  ”I believe you can infer the last side based on knowledge of the others.” Can you? If you flip all four edge pieces on the bottom face the bottom color shows up at all four side faces, and you wouldn’t be able to determine whether those four edge pieces got permuted, too.
  - TheSpiceIsLife 9y ago
    If you know the centre piece colours of five sides you know the remaining centre, the one you can’t see, must be the remaining colour.
    - 4ndr3vv 9y ago
      Quite. But we're talking about the permutation of the edge pieces on that face. You wouldn't be able to infer where they needed to be moved to if they were all just showing the bottom face colour.
      - TheSpiceIsLife 9y ago
        Oh, I see. Yes, that's obviously what your comment was saying. Thank you for clearing that up.
  - lokedhs 9y ago
    Good point. I stand corrected. In retrospect, it was obvious enough that I should have thought of it.
  - Someone 9y ago
    Thinking a bit more about it, this problem already pops up if the bottom face has either: - three edge pieces that share a color, with that color showing on the side. - two pairs of edge pieces that share a color, with the twice shared colors showing on the side. The first isn’t uncommon; if you pick three edges at random, the probability that they share a color is 1 * 6/11 * 2/10 = 6/55, and there are four ways to pick three edges from the bottom face, for (I think) a total probability of 24/55 - 4 * 6/55 * 1/9 (the probability that all four share the same color), or a probability of over 1/3 (if that seems high, consider the following: because of the pigeonhole principle, between the edges of any face of the cube there always is at least a pair sharing a color). That means that, even ignoring the second possibility, there’s at least a 1:24 probability of seeing this problem on a random cube.
  - gweinberg 9y ago
    Not all cube configurations are achievable by cube moves. That is, if you pull off one corner of a cube, rotate it, and stick it on again you get a cube which cannot be solved (except by disassembling it again). I think it actually is possible to infer the sixth side of a cube if you can see the other 5, because only only one configuration of the remaining side is actually acheivable.
otherme1 9y ago
They say the machine spend about 50ms adquiring images and solving, and 335ms moving the cube.

gowld 9y ago

Picking up and putting down a cube from a known location, and visually analyzing it, are both solved problems. It's a boring and arbitrary restriction. One could just as well require the manipulators start 100 yards away, which would be biased toward fast-moving robots.

TheSpiceIsLife 9y ago
Similarly, building a robot that has shafts fixed to the cube’s centres is a solved problem. Quite boring indeed.
- TheSpiceIsLife 9y ago
  Replying to myself to add: maybe we could see a triathlon with three stages of intellectual pursuit added to the three stages of physical activity. Run one hundred meters, solve a Rubik’s Cube, swim one hundred meters, solve a riddle, cycle five kilometres, then the first two who complete that have to head off in a game of Go. Why not? There’s people advocating eSports be included in the Olympics, so I’m open to anything at this stage.
  - Pamar 9y ago
    See also Chess Boxing: https://en.m.wikipedia.org/wiki/Chess_boxing https://en.m.wikipedia.org/wiki/Chess_boxing
    - TheSpiceIsLife 9y ago
      Amazing! Thank you! I'd not seen this before.
    - kgwgk 9y ago
      And Turing’s “round-the-house” chess: after you move, run around the house, if you get back before your opponent's move you are entitled to a new move.
phkahler 9y ago