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[CFOP] A tool to practice cross to transition to F2L

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[CFOP] A tool to practice cross and transition to F2L

How to use:

  1. Go here: http://net13.net/Cube/Cross/[1]
  2. Scramble your cube as indicated.
  3. Plan out your cross. It shouldn't be too hard, as it's only one move. :)
  4. Find an F2L pair.
  5. Execute your cross while tracking your F2L pair.
So what did you just do? You planned out the entire cross in your head, then you solved it while tracking an F2L pair, allowing you to immediately get started on F2L. That pretty much makes you a pro! :)

"Well, the cross only required one move…"
Ah, feeling confident, are we? In that case, go ahead and try level 2, where each cross requires two moves. :)

Notes:

  • If you're finding a level hard, you need to go back down one level. 15 seconds of inspection time should always be enough. Some things in life require you to really push yourself to succeed. This is not one of them. The cross is all about practice and repetition and every cross should be easy, because:
  • When you get your first, say, level 6 cross, you should be thinking: "I haven't seen a cross like this before, but if I did R2, it would be one of those level 5 crosses I'm an expert in." That is the trick for every level. You just have to find a move that will turn your cross into a cross a level lower, because you're already very good at that level or you shouldn't have moved up to this level. :)
  • Each level contains 1,000 random state scrambles.
  • "Scramble table columns" is just how wide you want the table to be. I've set it to 4 as default, as that gives the best use of screen space on my phone and my tablet. You can change it to whatever you like or set it to 0 if you're fine with just getting the scramble string. :)
 
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Lucas Garron

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#2
Not bad, the first 8-mover I tried really did take me 8 moves.

  • Each level contains 1,000 random state scrambles.
That sounds like it could run out.
Why not generate them on the fly?

If the way you handle this requires generating them ahead of time, could you also check all crosses, to make a color-neutral version?
i.e. each scramble in level N has at least one face with an N-move cross.
I've always wanted to train color neutrality, and it might be nice to motivate myself by saying "if I just look more, there will be a reasonably nice cross on another site".
 
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#5
Not bad, the first 8-mover I tried really did take me 8 moves.


That sounds like it could run out.
Why not generate them on the fly?

If the way you handle this requires generating them ahead of time, could you also check all crosses, to make a color-neutral version?
i.e. each scramble in level N has at least one face with an N-move cross.
I've always wanted to train color neutrality, and it might be nice to motivate myself by saying "if I just look more, there will be a reasonably nice cross on another site".
Do a rotation before each scramble to make a different cross
 
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Thread starter #7
  • Each level contains 1,000 random state scrambles.
That sounds like it could run out.
Why not generate them on the fly?
There are (at least) two ways to do this:

1. You randomly scramble the pieces of the cube not part of the cross. Then you apply X random moves to the cube, making sure they affect at least one cross piece each. Then you run an optimal cross finder to make sure a shorter cross than X isn't possible. I believe this is how csTimer does it with their "easy cross" option, except they skip the last part and often give you easier crosses than you ask for.

The problem with this method is that it doesn't give evenly distributed crosses and so some cross variants will show up a lot more often than they should, so I decided I didn't want to do it this way.

2. You generate completely random scrambles, then run your optimal cross finder on them and start over until you get a cross that requires exactly X moves.

This is IMO by far the best way to do it and so that's how I chose to do it. The problem with this method is that 1, 2, 3 and 8 move crosses are all quite rare (you get one 1 move cross for every 12,672 scrambles). This means that to do it dynamically would be quite slow, especially on mobile platforms.

Also, if there were 10 scrambles, I'm sure many people would recognize earlier scrambles. If there were 100 scrambles, I'm not sure I would ever recognize an earlier scramble. But with 1,000 scrambles? If you go: "Ok, so the scramble is R2 F' R2 B' R2 U2 F R2 U2... wait a minute! I just had this exact scramble like 500 solves ago!", then, well, you should probably move to a higher level and if you're already on level 8, you should probably go learn full ZBLL or something else that takes advantage of your amazing memory. :)

If the way you handle this requires generating them ahead of time, could you also check all crosses, to make a color-neutral version?
i.e. each scramble in level N has at least one face with an N-move cross.
I've always wanted to train color neutrality, and it might be nice to motivate myself by saying "if I just look more, there will be a reasonably nice cross on another site".
That's actually quite easy and a great idea: "There's a four move cross somewhere on this cube, I just have to find it." I'll think about it. :)

Also, could you do something so you don't have to moderate all my posts? I promise I'm not a spammer. :) I made a tiny edit to the post above and now the entire post has disappeared, probably because you have to moderate it again. :)
 
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#11
There are (at least) two ways to do this:

1. You randomly scramble the pieces of the cube not part of the cross. Then you apply X random moves to the cube, making sure they affect at least one cross piece each. Then you run an optimal cross finder to make sure a shorter cross than X isn't possible. I believe this is how csTimer does it with their "easy cross" option, except they skip the last part and often give you easier crosses than you ask for.

The problem with this method is that it doesn't give evenly distributed crosses and so some cross variants will show up a lot more often than they should, so I decided I didn't want to do it this way.

2. You generate completely random scrambles, then run your optimal cross finder on them and start over until you get a cross that requires exactly X moves.

This is IMO by far the best way to do it and so that's how I chose to do it. The problem with this method is that 1, 2, 3 and 8 move crosses are all quite rare (you get one 1 move cross for every 12,672 scrambles). This means that to do it dynamically would be quite slow, especially on mobile platforms.
For the 1, 2 and 3 move crosses, why not generate the random scramble, find the optimal cross, and then apply some of the moves of the optimal cross until it leaves a cross that takes the desired number of moves? For example, if you generated a scramble with a 5 move optimal cross, then you can apply the first 4 moves of that solution to produce a 1 move cross scramble. If there are multiple optimal crosses then just randomly choose one to apply moves from. You can then generate a scramble for that position.
 
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Thread starter #14
I think then it would become a game of memorizing the last moves of the scramble instead of trying to find the cross. :)
 

ottozing

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#15
Any particular reason for the diagram notation? IMO it's not needed since this tool is geared toward more advanced/intermediate solvers, who are presumable very comfortable with standard notation. Other than that, I definitely like the concept, although I don't think I'll be using it myself since cross to F2L is one of my much stronger points :p
 
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Thread starter #16
I actually made it for beginners, since I doubt people like yourself will have much use for it. :) I even put "for beginners" in the thread title but a moderator renamed it when he moved it to the correct forum. :)

If anyone doesn't like the cute images and still want to use it, they can just set "Scramble table colums" to 0 and that will just give them the scramble string. :)
 

Rune

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#19
I have solved 30 cubes at level 8 ("requires 8 moves"): 9 required 8 moves, 20 7 moves, (one 1 move).
For column 0 it would be desirable to show the end result of the scrambling (for controlling yourself).
Is it hard to get a choice of colour at the top when scrambling (not only W/Y)?
 
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I have solved 30 cubes at level 8 ("requires 8 moves"): 9 required 8 moves, 20 7 moves, (one 1 move).
Are you counting slice moves as one move? Because that's supposed to count as 2. :) The one requiring just one move I don't understand at all. I'm pretty sure that's not possible, unless it's scramble for white cross and you can solve something like blue in one move. :)

For level 0 it would be desirable to show the end result of the scrambling (for controlling yourself).
What's level 0? :)

Is it hard to get a choice of colour at the top when scrambling (not only W/Y)?
No, but does it matter much? I find that even if the colors are different, it's still pretty easy to look at the image and see if you messed up. :)
 
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