Most optimal way to find and handle Fridrich F2L pairs (Intuitive)

Discussion in 'General Speedcubing Discussion' started by xXdaveXsuperstarXx, Jun 7, 2009.

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  1. xXdaveXsuperstarXx

    xXdaveXsuperstarXx Member

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    So, when I'm solving F2L, finding the Edge and Corner is very important. But what you must understand, is that once you have the cubies located, you have to pair them up. I have found that it is easiest to look for a corner on top and then find it's edge. This is not the best for look-ahead, but when the corner is on top you have a relatively easy case to execute and pair. Granted I always go for easy corner and edge pairs, but when there are no easy ones to spot I resort to this. Now for me it's also helped to do one pair and then do the slot next to it, instead of have to fill two slots diagonal from each other. You can see I plan out my F2L very carefully. I want to know what you think.
     
  2. Why can't you just look for the pieces and solve them as you go? Why waste time on planning?

    P.S. - I do not look for a corner then an edge or vice-versa, I just look for the pieces...
     
  3. xXdaveXsuperstarXx

    xXdaveXsuperstarXx Member

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    This is mainly for execution, and people who are dexterous. As I said, I'm a "2-Gen F2L kind of guy" So to speak. ;)
     
  4. cmhardw

    cmhardw Premium Member

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    Now that I think about it I'm pretty sure that if I haven't spotted any pieces yet that I usually look for the corner first, then try to spot the edge. I don't do this every single time, if I see an edge first then I'll try to find the corner that goes with it. However, I think I have a more "corner biased" style of trying to look ahead than I do "edge biased" - I'm not a 50-50 split I guess I am trying to say.

    Chris
     
  5. xXdaveXsuperstarXx

    xXdaveXsuperstarXx Member

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    Okay, I'll just agree wich cmhardw because he can say it more simply.
     
  6. JLarsen

    JLarsen Premium Member

    Just a counterpoint, you've stated your method, now how good does it actually work out for you? Or otherwise stated more bluntly, what's your average?
     
  7. kjcellist

    kjcellist Member

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    I also agree with cmhardw. I almost always look for a corner first and then find the edge that goes along with it.
     
  8. cmhardw

    cmhardw Premium Member

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    I average about 15.5 for 3x3. Here are some thoughts comparing Corner Bias to Edge Bias.

    Viewability:
    When looking for the corner first you can see at most 12 of the 24 corner stickers (assuming you view the cube slightly at a diagonal). This is 1/2 of the possible stickers a corner be in place of, or 50% sticker viewability. Assume here that we have solved the cross, and have not yet solved any F2L slot.

    For edges you can see at most 10 of the 16 possible stickers, viewing at a diagonal, where an unsolved edge could be. This is 62.5% sticker viewability.

    Before I classify the edge bias as better than corner bias now let's look at how many of those stickers determine which piece you have.

    Corners:
    Of the 12 visible stickers, 1 corner has all 3 stickers viewable, and 3 corners have 2 stickers viewable (allowing you to determine which corner you have). This means that you can correctly identify 4 of the 8 corners at a glance without a cube rotation.

    Edges:
    Of the 10 visible stickers, 3 edges have both stickers visible, and 4 edges have 1 sticker visible. Notice that I am ignoring the cross edges, if that was not clear already. This means that at any given time you can correctly identify 3 of the 8 unsolved edges.

    From a "piece" standpoint I would say that Corner Bias is better because you can identify 4/8 pieces or 50% of the pieces at any given moment. For Edge Bias you can identify 3/8 unsolved edges or 37.5% identifiable at any given moment. Of course I mean here identifiable without a cube rotation.

    ----

    Now consider when you have solved the first corner edge pair at FR. If you view the FR slot as being right in front of you, with the cube on a diagonal, then you now can identify 3 corners of the 7 unsolved, and 2 edges of the 7 unsolved. This places the corner visibility higher than the edges for identifying pieces. For sticker visibility for corners there are 10/21 visibility or 10 stickers visible of the total 21 unsolved stickers. This is 47.6% sticker visibility. For edges there are 8/14 visibility or 8 of the 14 unsolved stickers are visible or 57.1% sticker visibility.

    Sticker visibility seems to prefer Edge Bias, but visibility taking into account ability to identify pieces without a cube rotation prefers Corner Bias.

    I would say, in my opinion, that I would prefer to be able to identify pieces without rotating, thus Corner Bias, than to see more of the remaining unsolved stickers when using Edge Bias. So in short, I think the visibility argument shows that "Corner Bias" lookahead is better if you prefer ability to identify pieces without a cube rotation. Maybe some experts use Edge Bias, and can argue an advantage over seeing more stickers? The downside here is that you must rotate more to identify pieces.

    I will try to look into the number of stickers visible by not just looking at a side of the cube in the static sense, but looking at the cube through the flow of a 90 degree cube rotation of either y or y'. This would be something that all solvers do, and is very important to lookahead as well.

    This post is already very long, so I'll stop here though and post the rest later.

    Chris
     
  9. xXdaveXsuperstarXx

    xXdaveXsuperstarXx Member

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  10. A general key for what I do (in cfop) solves to make f2l look ahead easier (rather identifying pieces) goes something like this:
    Cor corners
    -Look for sticker that matches cross colour.
    For edges
    -Any edge that doesn't have the colour opposite the cross.

    That about sums up my look ahead in a nut shell. '
    (of course I look at the adjacent stickers on the corners to know were to place them after i recognize that they belong in the first layer)
     
  11. enigmahack

    enigmahack Member

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    I appreciate the mathematics on this one... I've been having issues with my F2L being slow, and my whole average is hanging at 21 seconds, but I just can't break the barrier.

    Anyway, I'm going to go home and see if I can adopt this somehow so that I'm corner biased so instead of getting lost on a pair, I'll instinctively look for a corner instead and go from there.

    We'll see how it goes :)
     
  12. xXdaveXsuperstarXx

    xXdaveXsuperstarXx Member

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    Yeah, when you don't see any pairs laying around you should go right into making one instead of just looking two to be together.
     
  13. deadalnix

    deadalnix Member

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    Nice post Chris !

    However, I want to introduce some argument that will probably complexify the whole stuff.

    First of all, edge determine if you can handle the F2L case in 2gen or not. Thus being edge biased allow you to spot easy F2L cases in a better way than corner does and avoid regrips. In addition, edges doesn't change orientation in most F2L manipulation, leading to no changement at all for edges in slot when you regrip, so you can keep them in ming easily. Corner can change orientation in such operation, leading to complex 3D thinking during the solve.

    I tend to be easy to track pieces oriented. That means that I keep tracking pieces that are easy to track, and use them as a base to construct F2L pairs, combined with pieces in U layer ou frontal slots. This method allow me to be aware of piece that I actually don't see, thus improving my general nowledge of the current state of the cube.

    Bests pieces to use as easy to track are correctly oriented edges in slot. Those keep correctly oriented if you regrip so you can use them as jockers, giving you an 2gen F2L in any situation. When you insert an F2L pair in this slot, then look for the corresponding corner, so you can have 2 F2L in 2gen.

    Corners with U sticker on D are also easy. But usually lead to crappy F2L cases, so I prefers avoid using them, unless I have no other solution.

    Correctly oriented edges on U are really easy to track. And as long as you have some of them, you know you can solve F2L in 2gen. 1 is potentially added with every F2L pairs inserted. Keep tracking them, they are crusial.

    Do the same for corner on U. t seems like a lot of pieces, but actually most of them dont move during the solve. Pieces in slot don't move. Few pieces on U move during F2L insertion, and pieces on U keep being in U.
     
  14. Not to sound mean or anything..but when you average 25-27 seconds..you aren't really justified in giving advicce on how to lookahead.

    Great post though Chris :) Now that I think about my solves, I notice I always search for a corner piece, though when scanning for one I do notice the edge pieces and that allowes me to sort of have a genearl idea of where to look for them later on
     
  15. deadalnix

    deadalnix Member

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    Not to sound mean or anything, just considers what is written, not who is writting, you'll write less ****. And that's considering what is written, no who's writting.
     
  16. Kirjava

    Kirjava Colourful

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    Wouldn't it be better to not have any bias? I know when I'm building the second block that I'm not looking for any specific type of piece. It's more like I'm looking for multiple pieces that fit together. When I see a piece that is part of the block I'll taken a mental note of it but won't start looking for pieces that connect to it - I'll keep looking until I see a group that fits together nicely. Sometimes this includes the first piece I came across, sometimes it doesn't.

    This might be harder to do in F2L as there are more places to look, but I don't have bias when I do F2L either.
     
  17. qqwref

    qqwref Member

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    Nah, sometimes the person who's writing is really important. If someone is trying to provide expert speedcubing advice of any kind, and they're not actually good at speedcubing, it means their advice is unlikely to be helpful. It still could be good advice, of course, but it's more likely that it would be misinformed and based on guesswork instead of experience. It's the same principle behind getting a sports coach: if you want to be good at football (for instance), you'd rather have someone who was once a top professional player, as opposed to someone who used to spend half an hour a week kicking a ball around with their friends.
     
  18. FatBoyXPC

    FatBoyXPC Member

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    qq: I disagree with that to an extent. Have you heard the statement: "Those who can't do, teach." I don't necessarily like that statement either. I agree that most people would rather have a coach that used to be a pro player, but you most certainly don't have to be a pro player to be a great coach. Being a good coach and a good player are different entities. While I can agree that being good at one can make being good at the other easier, but I don't think it must be that way.
     
  19. RyanReese09

    RyanReese09 Premium Member

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    People who are pros know more then non pros. Tips and tricks are picked up along the way when you become a pro. It stands to reason (and I agree with qq) that I'd much rather have a fast(er) person (than me) giving me tips on how to get faster.

    There is very very little (if at all) room for a slower person to give me tips, besides obvious flaws in my solving which I know about.
     

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