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The CFOP Method (Cross – F2L – OLL – PLL), sometimes known as the Fridrich method, is one of the most commonly used methods in speedsolving a 3×3×3 Rubik's Cube. This method was first developed in the early 1980s combining innovations by a number of speed cubers. Czech speedcuber Jessica Fridrich is generally credited for popularizing it by publishing it online in 1997.[1] The method works on a layer-by-layer system, first solving a cross typically on the bottom, continuing to solve the first two layers (F2L), orienting the last layer (OLL), and finally permuting the last layer (PLL).

Contents

1 History 2 The method 3 Competition use 4 References 5 External links

History[edit] Basic layer-by-layer methods were among the first to arise during the early 1980s cube craze. David Singmaster published a layer-based solution in 1980 which proposed the use of a cross.[2] The major innovation of CFOP over beginner methods is its use of F2L, which solves the first two layers simultaneously. This step was not invented by Jessica Fridrich. According to Singmaster's report on the 1982 world championship, Fridrich was then using a basic layer method, while Dutch competitor Guus Razoux Schultz had a primitive F2L system.[3] The last layer steps OLL and PLL involve first orienting the last layer pieces, then permuting them into their correct positions. This step was proposed by Hans Dockhorn and Anneke Treep. Fridrich switched to F2L later in 1987. Her main contribution to the method was developing the OLL and PLL algorithms, which together allowed any last layer position to be solved with two algorithms and was significantly faster than previous last layer systems.[4] The method[edit]

Cross solved (view from bottom)

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First Two Layers solved

Orientation of the Last Layer complete

The method consists of 4 steps:

The Cross - This first stage involves solving the four edge pieces in one outer layer of the puzzle, centring around a commonly coloured centre piece. First Two Layers (F2L) - In F2L, corner and edge pieces are paired up and later moved to their correct location. There are 42 standard cases for each corner-edge pair including the case where it is already solved. It can also be done intuitively. Orientation of the Last Layer (OLL) - This stage involves manipulating the top layer so that all the pieces therein have the same colour on top, at the expense of incorrect colours on other sides. This stage involves a total of 57 algorithms. A simpler version, called "two-look OLL" orients edges and corners separately. It uses nine algorithms, two for edge orientation and seven for corner orientation. Permutation of the Last Layer (PLL) - The final stage involves moving the pieces of the top layer while preserving their orientation. There are a total of 21 algorithms for this stage. They are distinguished by letter names, usually based on what they look like with arrows representing what pieces are swapped around (e.g. A permutation, F permutation, T permutation, etc.). "Two-look" PLL solves the corners and edges separately. It uses six algorithms, two for corner permutation and four for edge permutation.

Competition use[edit] CFOP is heavily used and relied upon by many speedcubers, including Rowe Hessler, Mats Valk, and Feliks Zemdegs for its heavy reliance on algorithms, pattern recognition and muscle memory; as opposed to more intuitive methods such as the Roux or Petrus method. The majority of top speed cubers on the WCA ranking list are CFOP solvers.[5] References[edit]

^ Shotaro "Macky" Makisumi. "Speedcubing". cubefreak.net. Archived from the original on 2007-07-03. Retrieved 2007-08-31.  ^ "Beginner's Rubik's Cube Solution". Archived from the original on 26 September 2015. Retrieved 15 June 2012.  ^ Singmaster, David. "Cubic Circular Issue 3, Spring 1982".  ^ Fridrich, Jessica. "20 years of speedcubing". Retrieved 15 June 2012.  ^ WCA Website Team. "World Cube Association - Official Results". worldcubeassociation.org. 

External links[edit]

Jessica Fridrich's official site CFOP method on Speedsolving.com Wiki All OLL and PLL algorithms can be found on http://algdb.net/ How to solve Rubik's Cube

v t e

Rubik's Cube

Puzzle inventors

Ernő Rubik Uwe Mèffert Tony Fisher Panagiotis Verdes Oskar van Deventer

Rubik's Cubes

Overview 2×2×2 (Pocket Cube) 3×3×3 (Rubik's Cube) 4×4×4 (Rubik's Revenge) 5×5×5 (Professor's Cube) 6×6×6 (V-Cube 6) 7×7×7 (V-Cube 7) 8×8×8 (V-Cube 8)

Cubic variations

Helicopter Cube Skewb Square 1 Sudoku Cube Nine-Colour Cube Void Cube

Non-cubic variations

Tetrahedron

Pyraminx Pyraminx Duo Pyramorphix BrainTwist

Octahedron

Skewb Diamond

Dodecahedron

Megaminx (Variations) Pyraminx Crystal Skewb Ultimate

Icosahedron

Impossiball Dogic

Great dodecahedron

Alexander's Star

Truncated icosahedron

Tuttminx

Cuboid

Floppy Cube (1x3x3) Rubik's Domino (2x3x3)

Virtual variations (>3D)

MagicCube4D MagicCube5D MagicCube7D Magic 120-cell

Derivatives

Missing Link Rubik's 360 Rubik's Clock Rubik's Magic

Master Edition

Rubik's Revolution Rubik's Snake Rubik's Triamid

Renowned solvers

Erik Akkersdijk Yu Nakajima Bob Burton, Jr. Jessica Fridrich Chris Hardwick Kevin Hays Rowe Hessler Leyan Lo Shotaro Makisumi Toby Mao Tyson Mao Frank Morris Lars Petrus Gilles Roux David Singmaster Ron van Bruchem Eric Limeback Anthony Michael Brooks Mats Valk Feliks Zemdegs Collin Burns Lucas Etter Max Park

Solutions

Speedsolving

Speedcubing

Methods

Layer by Layer CFOP Method Roux Method Corners First Optimal

Mathematics

God's algorithm Superflip Thistlethwaite's algorithm Rubik's Cube group

Official organization

World Cube Association

Related articles

Rubik's Cube in popular culture The Simple Solution to Rubik's Cube 1982 World Rubik's Cube