Lars Petrus facts for kids
Lars Erik Petrus (born 4 November 1960) is a Swedish speedcuber. He is known as a famous and skilled Rubik's Cube solver.
Lars Petrus's Journey
Petrus grew up in Gammelstaden, a town near Luleå in Sweden.
He started speedcubing in the early 1980s. He learned how to solve the cube quickly during a summer when he had some free time. In 1982, he became the best Rubik's Cube solver in Sweden. He then placed fourth at the first big Rubik's Cube World Championships. This competition was held in Budapest, Hungary.
Lars Petrus later shared his special way of solving the cube online. This method is called the Petrus system. It became quite popular with many speedcubers. However, it is not as popular now because new methods like ZZ, Roux, and CFOP are used more often.
In November 2005, Petrus won the 3x3x3 Fewest Moves category at the World Championships. This event took place in Lake Buena Vista, Florida, USA. He won a US$500 prize. He also competed in the 2006 International Rubik's Cube Competition in San Francisco. Since 1995, he has lived in the SF Bay Area, California, USA. There, he works as a software developer.
The Lars Petrus System
The Petrus System is a unique way to solve the Rubik's Cube. It was created as a different option from the common "layer-by-layer" methods used in the early 1980s. These older methods often involved building the cube in layers. But this could make it hard to move other pieces later on.
Petrus wanted a method that allowed more freedom. So, he designed his system to solve the cube starting from one corner and working outwards. This way, he could move many sides of the cube freely as he progressed. This method is often used when people try to solve the cube in the fewest possible moves.
How the Petrus Method Works
The Petrus system uses seven main steps to solve a Rubik's Cube:
- Build a 2x2x2 block (a small cube of solved pieces).
- Expand this to a 2x2x3 block without messing up the first block.
- Fix the orientation of the edges (make sure they are facing the right way).
- Solve two complete layers of the cube.
- Arrange the remaining corner pieces into their correct spots (Permute Corners).
- Twist the remaining corner pieces so they are facing the right way (Orient Corners).
- Arrange the final edge pieces into their correct spots (Permute Edges).
Petrus created three simple and flexible moves (called algorithms) to help with the last three steps. He named these special moves Niklas, Sune, and Allan.
Over the years, many changes have been made to the Petrus method. These changes help speedcubers solve the cube even faster. More algorithms have been added to save seconds. Sometimes, steps 5 and 6, or 6 and 7, are combined to make the solution quicker.
