2-Sided PLL Recognition

2017-04-02T15:51:17Z

KungFooManchu: fixed typo

2-Sided PLL Recognition (sometimes called "1-Look PLL") is the task of recognizing a [[PLL]] from only two adjacent sides (e.g. F and R). This allows a cuber to determine what moves to do as soon as (s)he reaches PLL, without extra [[AUF]] turns or cube rotations.

==Why 2-Sided PLL Recognition is Possible==

2-Sided PLL Recognition is possible because:

* There are three visible corners, which are uniquely determined. This also determines the hidden one.
* There are two visible edges.
* The two hidden edges could be swapped in two different ways. However, given all the visible information there is only one possible way for a valid PLL. This is due to [[Permutation Parity | parity]].

Therefore, it is possible to tell exactly where each LL piece is (and which PLL case it is).
Unfortunately, this is only "barely possible". Unlike OLL (viewed from 3 sides), very few stickers are redundant. For 2-sided PLL recognition, t is sometimes necessary to look at 5 (out of 6) stickers carefully, because changing any one of them could create another valid case.

==Existing Systems==

* [http://www.kungfoomanchu.com/home.html#333pllrec Andy Klise]
** [http://www.kungfoomanchu.com/guides/andy-klise-pll-recognition.pdf Direct PDF link].
* [http://stachu.cubing.net/onelookpll/index.html Stachu Korick]
** [http://stachu.cubing.net/onelookpll/StatuePLL.pdf Direct PDF link].
* [http://sarah.cubing.net/3x3x3/pll-recognition-guide Sarah Strong]
** [http://sarah.cubing.net/3x3x3/pll-recognition-guide.pdf PDF version].
* [http://www.speedsolving.com/forum/showthread.php?47641-Improved-2-Sided-PLL-Recognition-System Lucas Garron - May 2014]
** Based on [http://www.kungfoomanchu.com/ Andy Klise's] system.
* [http://www.speedsolving.com/forum/showthread.php?41108-Two-sided-PLL-recognition-guide mark4952]
** [http://www.speedsolving.com/forum/attachment.php?attachmentid=2753&d=1364326050 Direct PDF link].
** [http://www.speedsolving.com/forum/showthread.php?47674-New-2-Sided-PLL-Recognition-Guide&p=979385#post979385 paritycase]
* [https://www.dropbox.com/s/r1j01hd5lhamjjt/PLL%202-Sided%20Recognition%20%5BV1.0%5D%20by%20Parity%20Case%20.pdf Direct link to PDF in Dropbox].
* [https://www.youtube.com/watch?v=4bNblQQ_P-o crazybadcuber] (video)
* [https://www.youtube.com/watch?v=ptJ09-4mciI Joseph Skyler] (video)
** Based on Sarah Strong's system?

Also [http://www.speedsolving.com/forum/searchresults.php?q=2+sided+pll+recognition search for "2-Sided PLL Recognition"] for more speedsolving.com threads.

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2-Sided PLL Recognition