Speedcubing

Introduction

Rubik’s cube is a combination puzzle invented in 1974 by a professor of architecture Ernő Rubik. It is a 6 sided cube with 9 stickers on each face. Each face is able to turn independently, resulting in 43 quintillion possible permutations. Speedcubing is the art of solving a Rubik’s Cube in the shortest possible time. The current world record at the time of writing is 5.55 seconds for 3x3 single solve.

In speedcubing competitions, competitors are required to complete 5 solves per round. Every solve is known as a single and the fastest time will be known is fastest single. However, winners are determined using an average of 5. Under this condition, the fastest solve and slowest solve timings are removed and the remaining 3 are averaged. This is done so eliminate the role of good luck and bad luck in causing the fastest and slowest solve respectively. As a result of having single and average of 5, each competition category has 2 world records - the world record single and the world record average.

Methods used

When someone first learned to solve the Rubik’s Cube, chances are he started with what is known as a layer by layer method. This method solves the 3 layers of a Rubik’s Cube in a sequential order. First, the bottom layer is completed. The second layer is completed next by inserting edges into the middle layer. After the first two layers are completed, a player solves the third layer and completes the Rubik’s Cube. While this method is very easy to learn, it is highly inefficient, hence speedcubers generally steer away from this method.

The most common speedcubing method is the CFOP method, developed in the early 1980s and popularized by Jessica Fridrich, in which the method is sometimes named after(the Fridrich method).

CFOP is an abbreviation for Cross, First two layers(F2l), Orienting the last layer(OLL) and Permuting the last layer(PLL). CFOP can be considered a variation of the layer by layer method. Instead of solving the first layer, followed by the second layer, CFOP recognizes that the corners of the first layer and the edges of the second layers can be solved simultaneously, improving efficiency and time. Solving the last layer in CFOP uses 57 algorithms for OLL and 21 for PLL. This allows the last layer to be completed in 2 steps, rather than 4 steps that beginners generally use.

Currently, the best speedcubers out there uses a variation of the CFOP method to obtain ever faster timing. Variations include X-cross, mutlislotting, ZBLL and more. Each variation aims to make the method more efficient and faster.

Another class of speedcubing method is known as block building. Two famous block building methods are the Roux method by Gilles Roux and Petrus Method by Lars Petrus. The core concept of these methods are the building of small blocks of pieces on the Rubik’s Cube and expanding them till the Rubik’s Cube is solved. 

Progression in timing

graph of timing improvement

As we can see, the timings improved a lot since 1982. This can be attributed to two things: better Rubik’s Cube and more efficient variation to proven speedcubing methods.

Better Rubik’s Cube

In the past, the only Rubik’s Cube that are available are Rubik's branded cubes. These cubes have no springs inside, this resulted in the need for perfect aligning of the layers before a move can be executed.

Over the years, new manufacturers have appeared and innovated with springs inside the cube and also better mechanisms that allow turns even when the layers are not perfectly aligned. This allows for faster turning as it is possible to ‘cheat’ by making the next move before a move is actually completed.

However, it is my belief that the improvement in timing due to improvement in cube technology has reached its limit and marginal improvement in timing will result from better Rubik’s Cube.

More efficient methods

As speedcubers experiment with the Rubik’s Cube, they discover more efficient methods to solve the Rubik’s Cube. First, there was the CFOP method that made an improvement to the layer by layer method. Now, there are multislotting techniques that aim to solve the F2L in CFOP in a more efficient manner by solving multiple corners and edges simultaneously. Techniques also exist to prevent ‘bad’ cases from appearing, thus improving timing by avoiding difficult cases.

I personally think that the only way for timing to improve is to improve the efficiency of speedcubing methods.Better cubes are not enough.

Final thoughts

Speedcubing is to me an art, it is not about algorithms or complicated mathematics. It is the art of visualizing movement and relationship between pieces and movement. To be good at solving the Rubik’s Cube, you need not be good at mathematics; you just have to see the interconnectedness of every piece on a Rubik’s Cube.

Try solving a Rubik’s Cube today; it is amazingly addictive once you learnt how to solve it. 


About the author

Kai Xiang is the Singapore champion for Rubik's Cube and has been speedcubing for 8 years and participated in 15 competitions, 12 of which are international. He loves speedcubing and has authored the site How to solve a Rubik's Cube | Simple solution guide that teaches others the wonder of the Rubik's Cube.


Feel free to publish this article on your own site if you would like to. However, please include the about author section and link back to my site. Thank you

See article in Google Doc