Speedcubing

Speedcubing (also known as speedsolving, speed cubing or speed-cubing) is the activity of solving a Rubik's Cube or related puzzle as quickly as possible. Here, solving is defined as performing a series of moves that transforms an incomplete cube into a state where each of the cube's six faces is one single, solid color.

Regular cubes are sold commercially in variations of 2×2×2, 3×3×3, 4×4×4, and 5×5×5. Variations of the puzzle have been designed with as many as 20 layers, but the largest denomination cube that has been physically produced is a 7×7×7. [ cite web|url=http://www.olympicube.com/ |title=Olympic Cubes |accessdate=2007-11-27 |last=Verdes |first=Panagiotis ] [ cite web|url=http://etienne.deforas.free.fr/rubiks/7×7×7/My_7×7×7.html |title=Homemade 7×7×7 |accessdate=2007-11-27 |last=de Foras |first=Etienne ] The current world record for a single solve of the 3×3×3 is now 7.08 seconds, set by Erik Akkersdijk at the Czech Open on July 12-13, 2008. [ cite web|url=http://www.worldcubeassociation.org/results/regions.php |title=WCA List of World Records |accessdate=2008-07-15 ] [ cite web|url=http://www.worldcubeassociation.org/results/c.php?allResults=All+Results&competitionId=CzechOpen2008 |title=WCA Results for Czech Open 2008 |accessdate=2008-07-15 ]

Speedcubing is the most prominent activity of the international Rubik's Cube community. Members come together to hold competitions, work to develop new solving methods, and seek to perfect their technique. As a part of the community, puzzle builders try to invent new forms of permutation puzzles.

History

The Rubik's Cube was invented in 1974 by Hungarian professor of architecture Ernő Rubik. A widespread international interest in the cube began in 1980, which soon developed into a global craze. On June 5 1982, the first world championship was held in Budapest. The height of the craze began to fade away after 1983, but with the advent of the Internet, sites relating to speedcubing began to surface. Simultaneously spreading effective speedsolving methods and teaching people new to the cube to solve it for the first time, these sites brought in a new generation of cubers, created a growing international on-line community, and raised the profile of the art. Twenty years after the first World Championship, the 2002 Dutch Open competition was the first in a new wave of organized speedcubing events, which include regular national and international competitions. [ cite web|url=http://www.worldcubeassociation.org/results/competitions.php |title=WCA List of All Recognized Competitions |accessdate=2007-11-27 ] There have been three more World Championships since Budapest's 1982 competition, the first held in Toronto in 2003, the second in Lake Buena Vista, Florida in 2005, and after 25 years the tournament returned to Budapest in 2007.

Solving Methods

The standard Rubik's cube can be solved using a number of methods, not all of which are suited for speedcubing. One of the most-used speedcubing methods is the Fridrich method, named after its inventor, Jessica Fridrich, who finished 2nd in the 2003 Rubik's Cube World Championships. Another popular method is the Petrus system (also commonly known as the "Lars Method"), named after its inventor, Lars Petrus, a method that is considered by some to be more intuitive than the structured Fridrich method. Other significant (though less widely-used) methods are various corners-first methods, simpler layer-by-layer approaches, and the Roux method.

Below are overviews of some commonly used speedcubing methods. For a more in-depth discussion of a particular method, see the appropriate article.

Fridrich method

The Fridrich method first works to solve a cross-shaped arrangement of pieces on the first layer. The remainder of the first layer and all of the second layer are then solved together in what are referred to as "corner-edge pairs" or slots. Finally, the last layer is solved in two steps — first, all of the cubies in the layer are oriented to form a solid color (but without the individual pieces being in their correct places on the cube). This step is referred to as orientation and usually is performed with a single algorithm known as OLL (Orientation of Last Layer). Then, all of those cubies are permuted to their correct spots. This is also usually performed as a single algorithm known as PLL (Permutation of Last Layer).

The Fridrich method is a widely-used speedcubing method. Its popularity stems from the speed at which it can be easily performed. Besides the first step, which can be planned during the customary 15-second inspection time, the entire solve of the cube consists of executing predefined algorithms based on the state of the cube.

Petrus method

The Petrus method works by first solving a 2×2×2 block of the cube. This block is then extended to a solved 2x2x3 block. All edges are then oriented, and then the remaining two sides of the cube are then solved using only a few algorithms. Lars Petrus developed this method to address what he felt were inherent inefficiencies in layer-by-layer approaches, which he explains in his method's tutorial: "When you have completed the first layer, you can do nothing without breaking it up. So you break it, do something useful, then restore it. Break it, do something, restore it. Again and again. In a good solution you do something useful all the time. The first layer is in the way of the solution, not a part of it!". [http://lar5.com/cube/index.html] This method uses significantly fewer turns than a layers approach, and is often used as the basis for fewest moves competition solutions.

Roux method

The first step of the Roux method is the formation of a 3x2x1 block. The 3x2x1 block is usually placed in the lower portion of the left layer. The second step is to create another 3x2x1 on the opposite layer. The remaining four corners are then solved, which leaves six edges and four centers that are solved in the last step.

This method makes more efficient use of the standard 15 second inspection time, since one can plan the solution of 6 pieces rather than 4 for the Fridrich and Petrus method. It also isn't as dependent on algorithm memorizing as the Fridrich method, since all but the third step is done with intuition as opposed to predefined sets of algorithms. Because of this, however, the solve may not be executed as quickly as a solve done with the Fridrich method. It doesn't require as many cube rotations as the Fridrich method, so it is easier to look ahead while solving i.e. solving a collection of pieces and at the same time looking for the solution to the next step.

Corners-first method

This method involves solving the corners then finishing the edges with slice turns. Corners-first solutions were common in the 1980s, with one of the most popular methods that of 1982 world champion Minh Thai. Currently corners-first solutions are less common among speedsolvers. The best corners first method was created in the cube craze by Dutch cuber Marc Waterman. He averaged 16 seconds in the mid-late 80s. First, build a face on the left. Then, solve the remaining corners. Next, solve two right edges and place one remaining right edge in the right layer OR solve three right edges. Then, solve the last right edge(s) and orient middle edges simultaneously. Finally, permute middle edges. About 7 algorithms to memorize.

Competitions

According to the World Cube Association, competitors (in the same round) must solve cubes that are scrambled using a consistent algorithm (as in, every competitor solves the same scramble). Currently, the official timer used in competition is the StackMat timer. This device has touch-sensitive pads that are triggered by the speedcuber lifting their hands to start the time and placing their hands back on the pads after releasing the puzzle to stop the time. In addition to the electronic timer, there are human judges with stopwatches, who act as a back-up in case the timer doesn't work properly. These judges also ensure that the competitors are following competition regulations.

Official competitions are currently being held in several categories.

Competitions will often include events for speedsolving these other puzzles, as well:

* Megaminx
* Pyraminx
* Rubik's Clock
* Rubik's Magic
* Square-1

World records

These are the world records for speedsolving the four types of cubes as set during WCA-approved events.

Lubrication

Some speedcubers will lubricate their cubes to prevent wrist and finger injury. Lubricating the cube also allows it to be manipulated more quickly than a non-lubed cube. The WCA allows lubrication for WCA-sanctioned competitions. Usually, the lubricant's main ingredient is polysiloxane.

ABS, the main plastic in Rubik's cubes, should not be lubricated with lubricants containing any of the following:

*Methylene chloride, often used for welding ABS plastic
*Acetone, a good solvent for ABS plastic
*WD-40, incompatible with ABS plastic due to white spirit (also known as Stoddard solvent) content

Checking a lubricant's MSDS is often helpful in identifying cube-damaging ingredients.

Terminology

Here are some definitions generally used by the speedcubing community. For a more complete list of speedcubing terminology, see [http://www.cubefreak.net/glossary.html Shotaro "Macky" Makisumi's glossary] .

; Algorithm : A predefined sequence of moves used to effect a specific change on the cube. Often referred to as "alg".; BLD : Blindfold solving, i.e. memorize, blindfold, then solve.; Center piece : one of the six centers of the faces of the cube. The centers never move relative to each other on an NxNxN cube, where N is odd.; CLL : Corners of Last Layer. This is the first of two steps to solve the last layer of the cube. In the process, edges may not be unoriented. This is used in Corners First methods for the last layer, in which the first all corners are solved, followed by the edges (see: ELL).; Corner piece : One of the 8 corner pieces.; Cubie : One of the 20 mechanically independent pieces that make up the cube. The cubies do not include the center pieces, nor the central axis to which they are attached.; Cycle : To rotate pieces' positions on the cube. E.g. a 3-cycle would make cubie set A-B-C become C-A-B.; DNF : Did Not Finish, used in competition e.g. when a piece pop occurs and the competitor decides not to continue the solving of the puzzle.; DNS : Did Not Solve, used in competition when the competitor was unable to solve the puzzle in the required time.; Edge piece : One of the 12 edge pieces.; ELL : Edges of Last Layer. The second of two steps to solve the last layer of the cube, solving the edge pieces without disturbing the orientation of the corner pieces (see: CLL).; F2B : First two blocks.; F2L : First two layers.; F2L method : a method which solves the first and second layers simultaneously.; LL : Last Layer.; Method : A combination of steps that can be used to solve a cube.; Move : A turn or double turn of one of the six faces or three slices of the cube.; "N"-look, also known as "X"-Look : refers to the number of algorithms needed to complete a step in a particular solving method, often the last layer, e.g. '4-look LL'.; OLL : Orient Last Layer, usually used in reference to the respective step of the Fridrich method.; Orient : To flip or twist pieces so they turn 'in-place'.; PB : Personal Best - personal record time to solve a puzzle. This can either be a single attempt or a trimmed average, depending on context.; Permute : swap or cycle two or more pieces. ; PLL : Permute Last Layer. Usually used in reference to the respective step of the Fridrich method, in which case it would follow the OLL step.; Pop : When, during a speedsolve, one or more cubies come out of the puzzle. Also known as "piece pop".; Prime : A counter-clockwise move popularly denoted with a ', e.g. 'R Prime', denoted as R', R-, R^-1, Ri. Also known as "inverse" or "inverted".; Slice : The four center pieces and four edge pieces between two opposite faces of the cube.; Two-Second Penalty : A penalty of 2 seconds which is added to a solving time in competition when the cube is placed back on the timing pad with one or more misaligned faces.; UWR : Unofficial World Record.; WCA : World Cube Association, the international governing body for official cube competitions.; WR : World Record.

See also

*Rubik's Cube
*Jessica Fridrich
*Lars Petrus
*World Cube Association

Notes

External links

* [http://www.rubikssolver.com/Rubiks_Cube_Speed_Solving.html Speed Cube Solution Guide - with pictures]
* [http://www.speedcubing.com speedcubing.com - Speedcubing informational and Unofficial World Records site]
* [http://www.speedsolving.com Speedcubing Discussion Forum]
* [http://www.speedsolving.com/wiki Speedcubing Wiki]
* [http://www.ws.binghamton.edu/fridrich/cube.html Fridrich method]
* [http://lar5.com/cube/index.html Petrus method]
* [http://grrroux.free.fr/ Roux method]
* [http://rubikscube.info/ Waterman method]