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👩‍🎓 | How many times can you complete it in the shortest time?Relationship between Rubik's Cube algorithm and mathematics


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How many times can it be completed at the shortest?Relationship between Rubik's Cube algorithm and mathematics

 
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If you become more inquisitive, there is also a method called F2L that puts two at the bottom of the four corners at the same time, and children should learn how to interact well with the algorithm.
 

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CFOP method

CFOPThe (CFOP) method isRubik's CubeOne of the solutions.It is so called by taking the acronyms Cross, F2L, OLL, and PLL, which are the steps of the solution method.Also known as the Fridrich method.Currently, it is the most widely used solution for the speed of the Rubik's cube.

History

The CFOP method is the basic solution for the Rubik's cube.Layer By LayerIt was developed based on.Since it is also called the Fridrich method, it is often misunderstood that it is a solution devised by Jessica Fridrich, but each process was devised by a different person, and Jessica Fridrich mainly performed OLL and PLL algorithms. In 1997, the dawn of Speed ​​Cube, the entire procedure of CFOP was summarized and published on the website.[1] ..Many people at the time visited her website to learn how to solve it, so it became known as the Fridrich method.

The first process, Cross, is the same as the Layer By Layer devised by David Singmaster in 1980.[2].. The F2L was already in use by Guus Razoux Schultz at the 1982 World Championships, and according to him, it was invented by René Schoof in 1981.[3].. OLL and PLL were proposed by Hans Dockhorn and Anneke Treep in the 1980s.[4]After that, Jessica Fridrich developed many algorithms.

From such a history, there was a movement to deny calling the CFOP method the Fridrich method around 2008, and now the CFOP method is the mainstream.[5].

Flow to completion

In CFOP, 6 sides will be completed according to the following flow.For the name of each partRubik's CubeSee.

Cross

Align the edges of the first layer. It is called a cross because the state where the four edges are aligned forms the shape of a cross.In the Rubik's Cube, the center parts on each side do not move, so the sides of the cloth and the color of each center must match.This process isLayer By LayerIs similar to.

According to the rules of the official tournament, the time to see the cube (inspection time) is given for 15 seconds before starting to solve, but when solving with the CFOP method, it is common to read the procedure for aligning crosses at this time.At the top level, read up to the first F2L and up to X-Cross below.

When a beginner does it, usually make a cloth on the upper surface (U side), change the cloth so that it is on the lower surface (D side), and then enter F2L in the next process, but if you want speed, eliminate the change and go to the next Make a cloth on the bottom surface from the beginning to perform F2L look-ahead.This technique is called D-side cross.

F2L (First 2 Layers)

Layer By LayerThen, after the cloth, the first layer is completed (complete one side) and then the second layer is completed, but in F2L, this first layer and the second layer are aligned at the same time.The pair of four edges and corners between the crosses is called a slot, and since the pair parts are put into these four slots, they are called 4st pair, 4nd pair, 1rd pair, 2th pair, etc.

The basic procedure is 41 patterns, but there are also patterns that use slots that have not been entered or align the slots on the back side that you have, so the number is enormous if you include the application patterns.

OLL (Orientation of the Last Layer)

Align the colors on the top surface of the final layer.It is called the Orientation of the Last Layer because it corrects the orientation of all the edge corners of the final layer.The total number of patterns is 57.If you want to do it simply, you need to align the edges and then the corners in two steps, which is called 2 Look OLL.

PLL (Permutation of the Last Layer)

Align the location of the final layer.It is called the Permutation of the Last Layer because it corrects the location of all the edge corners of the final layer.The total number of patterns is 21.If you want to do it simply, you need to align the corners and then the edges, which is called 2 Look PLL.In Japan, in the "Rubik's Cube 2 Seconds Completion Method" published by Mr. naitsu in 2001, the procedure was introduced by assigning numbers 20 to 1 to each PLL, so it was taken from the acronym of Mr. naitsu for a long time. Each pattern was called by the numbers from "n21" to "n1" with "n" in the head. [6].. In 2012, the names A-Perm and U-Perm, which are based on the movement of parts used worldwide as standard on roudai.net, were put together and released, so they are also called in Japan. Came to take root[7].

Development technique

As mentioned above, CFOP's basic technique consists of four steps: Cross, F2L, OLL, and PLL, and each of these steps is called a sub-step.In recent years, more advanced sub-steps have been developed, such as aligning a part of the PLL while doing the OLL, or intentionally skipping the OLL.

X-Cross

The abbreviation for extended cross.When creating a cloth, it means aligning up to the first F2L using a pair block or block building of edge corners made from the scrambled state.Also, aligning up to the second F2L with a cloth is called Double X-Cross (or XXCross), and aligning up to the third is called Triple X-Cross (or XXXCross), but these rarely occur.

Winter Variation

The procedure to skip OLL when up to 2 F3Ls are filled, the edges and corners to be inserted in the last slot are already paired (in the state where they can be inserted with URU'R'), and the top edge orientation is all correct.The total number of patterns is 27. It is called Winter Variation because it was developed by Lucas Winter.In contrast to the above conditions, the procedure when the edges and corners are not paired but one hand apart (in the state where they can be inserted with R R R') is called Summer Variation.

VLS (Valk Last Slot)

A procedure that eliminates the condition for edges from the conditions for Winter Variation.The total number of patterns is 216. It is called Valk Last Slot because it was developed by Mats Valk.

COLL (Corners of Last Layer)

A sub-step that aligns the corner orientation and location at the same time from the state where the top edge orientation is aligned.The total number of patterns is 40.By doing this, in the PLL, only 21 patterns with only edge exchange appear out of all 4 patterns, and the probability that the PLL will skip is 6 times that of the normal OLL.

OLLCP (Orientation of Last Layer and Corner Permutation)

In COLL, the condition is that the edge orientations of the OLLs are aligned, but a sub-step that aligns the edge corner orientation and corner location from all OLLs regardless of the edge orientation.The total number of patterns is 331. Like COLL, only 4 patterns of PLL appear, and the probability of PLL skip is 6 times.

ZBLL (Zborowski-Bruchem Last Layer)

A sub-step that aligns the corner orientation and all edge corners at the same time from the state where the edges of the OLL are aligned.The total number of patterns is 493.It can be said that it is a procedure that can always skip the PLL.

1LLL (1-Look Last Layer)

In ZBLL, the condition is that the edge orientations of the OLLs are aligned, but a sub-step that aligns all the edges and corners from all the OLLs at the same time regardless of the edge orientation.The number of patterns is 1211 patterns even if symmetric or reverse rotation is regarded as the same, and 3915 patterns when they are different.It can be said that it is a procedure that can always skip the PLL.

Source

  1. ^ "An Overview of the Fridrich Method”. Cubefreak.net. NovemberBrowse.
  2. ^ "Beginner's Rubik's Cube Solution”. As of May 2015, 9オ リ ジ ナ ルMore archives.NovemberBrowse.
  3. ^ "René Schoof”. SpeedSolving.com Wiki. NovemberBrowse.
  4. ^ "Anneke Treep”. SpeedSolving.com Wiki. NovemberBrowse.
  5. ^ "CFOP method”. SpeedSolving.com Wiki. NovemberBrowse.
  6. ^ Rubik's Cube 20 Seconds Completion Method Final Stage(Wayback machine, June 2004, 4)- http://naitsu.hp.infoseek.co.jp:80/kansei.htm[Broken link]
  7. ^ "PLL list”. As of May 2013, 2オ リ ジ ナ ルMore archives.NovemberBrowse.

 

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