Straughan Recognition
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Straughan Recognition is the concept of recognizing a step by using the minimum number of stickers. Traditional recognition methods involve first determining the orientation of the involved group of pieces then checking several additional stickers to determine the permutation. Straughan recognition instead checks only the minimum number of stickers required to determine a case. The recognition concept can be used with various steps and puzzles.
Examples
CxLL
When Straughan recognition is applied to CxLL, as in 2x2 CLL or CMLL, just four stickers are necessary to determine the current case. The standard is to track the stickers that belong at FLU, FUR, RFU, and RUB. The locations of these four stickers will show the current CxLL case.
ZBLL
Six stickers are the minimum required to determine any ZBLL case. If the FU and RU stickers are added to the standard FLU, FUR, RFU, and RUB stickers that are involved in CxLL, the locations of those six stickers determine the current ZBLL case.
PLL
Five stickers are enough to recognize a PLL case. This is similar to two sided PLL recognition, but with the removal of one corner sticker.
L5C
The minimum number of stickers to recognize L5C is five. Four stickers from the last layer and one from the single unsolved corner belonging to the opposite layer.
L5E
For the last five edges, just four stickers are necessary.
Megaminx / Kilominx
Similar to 3x3 L5C, recognizing Megaminx or Kilominx CxLL requires just five stickers.
Early Corner Permutation
Straughan recognition can also be applied to early corner permutation recognition as used in methods such as CEOR and variants of Nautilus.
