Speedcubing

Erik Akkersdijk solving a 3×3×3 Rubik's Cube in 10.50 seconds.
A speedsolver completing a 3×3×3 Rubik's Cube.

Speedcubing (also known as speedsolving) 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 a scrambled puzzle into a state where each of the puzzle's six faces is one single, solid color.

Most cubes are sold commercially in variations of 2×2×2, 3×3×3, 4×4×4, 5×5×5, 6×6×6, and 7×7×7, although variations of the puzzle have been designed with as many as 17 layers.[1] The current world record for a single solve of the 3×3×3 in competition is 5.55 seconds set by Mats Valk during the Zonhoven Open 2013.[2][3]

Speedcubing is a popular activity among 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 combination 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, Hungary. 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 online 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.[4] There have been five more World Championships since Budapest's 1982 competition, which are traditionally held every other year, 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, Hungary in 2007. In 2009, the tournament was held in Düsseldorf, Germany. In 2011, the tournament was held in Bangkok, Thailand.

Solving methods

The standard Rubik's Cube can be solved using a number of methods, not all of which are intended for speedcubing. Although some methods employ a layer-by-layer algorithm, other significant (though less widely-used) methods include corners-first methods, and the Roux method.

CFOP system

The CFOP (Cross - F2L - OLL - PLL) system, also known as the Fridrich Method, was named after one of its inventors, Jessica Fridrich, who finished 2nd in the 2003 Rubik's Cube World Championships. The first step of the method is 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 always being in their correct places on the cube). This step is referred to as orientation and is usually performed with a single set of algorithms 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 set of algorithms known as PLL (Permutation of Last Layer).

The CFOP system 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.

Roux method

The Roux method was invented by French speedcuber Gilles Roux. The first step of the Roux method is to form a a 3×2×1 block. The 3×2×1 block is usually placed in the lower portion of the left layer. The second step is to create another 3×2×1 on the opposite side. The remaining four corners are then solved using a set of algorithms known as CMLL (Corners of the Last Layer, without regards to the M-slice), which leaves six edges and four centers that are solved in the last step.

This method is not as dependent on algorithm memorization as the CFOP method, since all but the third step is done with intuition as opposed to predefined sets of algorithms. The Roux method doesn't require as many cube rotations as the CFOP method, so it is easier to look ahead (solving a collection of pieces while at the same time looking for the solution to the next step) while solving.

ZZ method

The ZZ method is a modern speedcubing method originally proposed by Zbigniew Zborowski in 2006. The method was designed specifically to achieve high turning speed by focusing on move ergonomics. The initial pre-planned step is called EOLine, and is the most distinctive hallmark of the ZZ method. It involves orienting all edges while placing two opposite down-face edges. The next step solves the remaining first two layers using only left, right and top face turns. On completion of the first two layers, the last layer's edges are all correctly oriented because of edge pre-orientation during EOLine. The last layer may be completed using a number of techniques including those used in the CFOP method. An expert variant of this method (ZZ-a) allows the last layer to be completed in a single step with an average of just over 12 moves and knowledge of 177 algorithms.[5]

Petrus method

The Petrus method, named after its inventor Lars Petrus, is considered to be more intuitive than the structured CFOP method. The first step of the Petrus method is to solve a 2×2×2 block of the cube. This block is then extended to a solved 2×2×3 block. All edges are then oriented and the first and second layers are completed. Next, the top corners are put in the right place and the layer is oriented correctly (all stickers facing up) and finally the last edges are permuted (moved around). Lars Petrus developed this method to address what he felt were inherent inefficiencies in layer-by-layer approaches. This method is often used as the basis for fewest moves competition solutions.

Corners-first methods

Corners-first methods involve 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. Dutch cuber Marc Waterman created a corners-first method in the cube craze, and averaged 16 seconds in the mid-late 1980s.

Competitions

Anssi Vanhala solving a 3×3×3 Rubik's Cube with his feet in 36.72 seconds, at the 2009 Estonian Open.

According to the World Cube Association (WCA), competitors (in the same round) must solve cubes that are scrambled using a consistent algorithm (every competitor solves the same scramble). Currently, the official timer used in competitions 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 timer. In addition to the electronic timer, there are human judges with stopwatches who time the 15-second inspection period before each solve, as well as solves which may take longer than 10 minutes. These judges also ensure that the competitors are following competition regulations.

Official competitions are currently being held in several categories.

Category Cube Type
speedsolving 2×2×2, 3×3×3, 4×4×4, 5×5×5, 6×6×6, 7×7×7
one-handed solving 3×3×3
blindfolded solving 3×3×3, 4×4×4, 5×5×5
multi-blindfolded solving 3×3×3
solving with feet 3×3×3
solving in fewest moves 3×3×3
Speedsolvers completing Megaminxes at the 2011 Estonian Open.

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

World Rubik's Cube Championships

The WCA organizes the World Rubik's Cube Championship as the main international competition once every two years. The latest championship was held in Bangkok, Thailand, from October 14–16, 2011. The next championship will be held in Las Vegas, USA, from July 26-28, 2013.

Championship Year Host Dates Nations Puzzles Events Winner Winning time(s) Ref
I 1982 Budapest June 5 19 1 1 Minh Thai 22.95 [6]
II 2003 Toronto August 23–24 15 9 13 Dan Knights 18.76 [7]
III 2005 Lake Buena Vista November 5–6 16 9 15 Jean Pons 13.00 [8]
IV 2007 Budapest October 5–7 28 10 17 Yu Nakajima 11.50 [9]
V 2009 Düsseldorf October 9–11 32 12 19 Breandan Vallance 9.63 [10]
VI 2011 Bangkok October 14–16 35 12 19 Michał Pleskowicz 7.68 [11]

World records

The following are the official speedcubing world records that are approved by the World Cube Association.[2]

Event Type Result (Min:Sec) Person Competition Result Details (Min:Sec)
2×2×2 Single 00:00.69 Christian Kaserer Trentin Open 2011
Average 00:02.08 Christopher Olson Dixon Winter 2013 00:01.53 / 00:01.96 / 00:02.46 / 00:04.69 / 00:01.83
3×3×3 Single 00:05.55 Mats Valk Zonhoven Open 2013
Average 00:07.53 Feliks Zemdegs Australian Nationals 2012 00:07.56 / 00:06.78 / 00:07.16 / 00:11.44 / 00:07.86
4×4×4 Single 00:26.44 Sebastian Weyer Velbert Open 2013
Average 00:29.17 Sebastian Weyer Frankfurt Cube Days 2012 00:27.66 / 00:29.13 / 00:38.96 / 00:29.09 / 00:29.30
5×5×5 Single 00:51.09 Feliks Zemdegs Australian Nationals 2012
Average 00:57.63 Feliks Zemdegs Melbourne Cube 2012 00:56.58 / 00:58.03 / 00:55.86 / 01:07.02 / 00:58.27
6×6×6 Single 01:49.46 Kevin Hays Couve Cubing 2012
Average 01:55.13 Kevin Hays Couve Cubing 2012 01:53.88 / 02:02.06 / 01:49.46
7×7×7 Single 02:41.63 Lin Chen Hangzhou 2012
Average 02:56.85 Lin Chen Hangzhou 2012 03:14.44 / 02:54.47 / 02:41.63
Megaminx Single 00:42.28 Simon Westlund Danish Open 2011
Average 00:47.82 Bálint Bodor Hungarian Open 2012 00:51.90 / 00:49.55 / 00:47.50 / 00:45.88 / 00:46.40
Pyraminx Single 00:01.36 Oscar Roth Andersen Danish Special 2013
Average 00:02.96 Oscar Roth Andersen Danish Special 2013 00:03.38 / 00:01.36 / 00:03.00 / 00:02.86 / 00:03.02
Square-1 Single 00:08.65 Bingliang Li Guangdong Open 2010
Average 00:11.31 Bingliang Li Guiyang Open 2012 00:11.24 / 00:10.43 / 00:10.87 / 00:11.82 / 00:13.62
Rubik's Clock Single 00:05.27 Sam Zhixiao Wang Shanghai Winter 2011
Average 00:06.90 Pierre Bouvier Cannes Open 2013 00:07.25 / 00:06.15 / 00:06.61 / 00:07.44 / 00:06.84
3×3×3: Blindfolded Single 00:26.36 Marcell Endrey Euro 2012
4×4×4: Blindfolded Single 02:30.62 Marcell Endrey Slovenian Open 2013
5×5×5: Blindfolded Single 06:44.77 Marcell Endrey Zune Open 2012
3×3×3: Multiple Blindfolded Single 33/37 in 54:21 Marcin Kowalczyk Polish Open 2013
3×3×3: One-handed Single 00:09.43 Giovanni Contardi Italian Championship 2012
Average 00:12.67 Michał Pleskowicz Cubing Spring Grudziadz 2012 00:12.15 / 00:14.53 / 00:13.27 / 00:12.58 / 00:10.77
3×3×3: With feet Single 00:27.93 Fakhri Raihaan Celebes 2012
Average 00:35.15 Yunsu Nam Cubing Korea Xmas Eve 2011 00:38.77 / 00:33.63 / 00:33.05
3×3×3: Fewest moves Single 20 moves Tomoaki Okayama Czech Open 2012

Lubrication

Some speedcubers lubricate their cubes to prevent wrist and finger injury. Lubricating the cube also allows it to be manipulated more quickly than a non-lubricated cube. The WCA allows lubrication for official competitions.

Some of the popular lubricants among speedcubers are:

• Lubix Cube Lubricant
• CRC Heavy Duty Silicone Spray
• D-39 Silicone Spray
• Cyclo Silicone Spray
• Maru Lubricant
• Traxxas 50K Differential Oil
• Cubesmith Lubricant

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 the cubefreak.net glossary.

Algorithm
A predefined sequence of moves used to effect a specific change on the cube. Often referred to as alg or (less commonly) an algo.
BLD
Blindfolded 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 the Last Layer. This is the first of two steps of one of the methods of solving the last layer of the cube. In the process, edges may 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 pieces with exactly three stickers, called a "corner" piece because a corner is exposed.
Cubie
One of the mechanically independent pieces that make up a puzzle. The cubies do not include fixed 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, or when a blindfolded solver stops the timer with the cube still unsolved.
DNS
Did Not Start, used in competition when the competitor does not begin a solve, either by opting to skip it (common in Blindfold Cubing) or by not showing up when he or she is called, or not qualifying for the remaining (usually 3) solves of a certain round.
Edge piece
One of the 12 pieces with exactly two stickers, called an "edge" piece because only one edge is exposed.
ELL
Edges of the Last Layer. The second of two steps of one of the methods of solving the last layer of the cube, solving the edge pieces without disturbing the corner pieces (see CLL).
F2B
First two blocks. This is used in the Roux method.
F2L
First two layers.
Layer
One section of a cube consisting of a number of cubies that turn as a unit. (e.g. a standard Rubik's Cube has 3 layers)
LL
Last Layer.
Method
A combination of steps that can be used to solve a cube.
Move
A 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
Orientation of the Last Layer, usually used in reference to the respective step of the CFOP method.
Orient
To change the orientation of a piece.
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
To relocate certain pieces in a way to achieve a desired result.
PLL
Permutation of the Last Layer. Usually used in reference to the respective step of the CFOP method, in which case it would follow the OLL step.
Pop
When, during a speedsolve, one or more cubies come out of the puzzle.
Prime
A counter-clockwise move popularly denoted with a ', e.g. 'R Prime', denoted as R', R-, $R^{-1}$, or Ri. Also known as "inverse" or "inverted".
Slice
The four center pieces and four edge pieces between two opposite layers of the cube.
Two-Second Penalty
A penalty of 2 seconds which is added to a solving time in official competitions when the cube is placed back on the timing pad with one or more misaligned faces. It can also be given in other cases, such as when the competitor starts the timer too slow or does not correctly stop the timer after finishing the solve.
UWR
Unofficial World Record.
WCA
World Cube Association, the international governing body for official cube competitions.
WR
World Record. Can also "World Rank" when referring to the rank of a person's record in a database.

Notes

1. ^
2. ^ a b "Records". Retrieved 2013-04-02.
3. ^
4. ^ "Competitions". Retrieved 2007-11-27.
5. ^ "Rubik's Cube: Algorithms for the last layer". Retrieved 2009-06-02.
6. ^ "World Rubik's Cube Championship 1982". World Cube Association. Retrieved 2010-12-27.
7. ^ "World Rubik's Games Championship 2003". World Cube Association. Retrieved 2010-12-27.
8. ^ "Rubik's World Championship 2005". World Cube Association. Retrieved 2010-12-27.
9. ^ "World Rubik's Cube Championship 2007". World Cube Association. Retrieved 2010-12-27.
10. ^ "World Rubik's Cube Championship 2009". World Cube Association. Retrieved 2010-12-27.
11. ^ "World Rubik's Cube Championship 2011". World Cube Association. Retrieved 2011-01-24.