Lars Petrus
Encyclopedia
Lars Petrus made his name as an internationally accomplished speedcuber
in 1982 when he became the national champion of Sweden
, and went on to finish fourth overall at the first official Rubik's Cube
World Championships held in Budapest
, Hungary
. He later published his unique method, known as the Petrus system, on the Internet. It has become an extremely popular method among intermediate and upper-level speed cubers, although its more recent usage has diminished considerably at the professional level due to the increased predominance of brute force algorithm
-based methods. Petrus won the 3x3x3 Fewest Moves category at the 2005 World Championships held November, 2005 at Lake Buena Vista, Florida
, claiming the $500 purse. He currently resides in Silicon Valley
, California
. Lars Petrus is currently taking time off from employment at Google
.
Petrus invented three simple and flexible algorithms to complete the last three steps, which he named Niklas, Sune, and Allan.
While the method stands alone as an efficient system for solving the Rubik's Cube, many modifications have been made over the years to stay on the cutting edge of competitive speedcubing
. Many more algorithms have been added to shave seconds off the solution time, and steps 5+6 or 6+7 are often combined depending on the problems each case presents. Petrus' personal best speedsolve is 13.60 seconds, achieved in 2006.
Speedcubing
Speedcubing is the activity of solving a Rubik's Cube or related puzzle as quickly as possible...
in 1982 when he became the national champion of Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
, and went on to finish fourth overall at the first official Rubik's Cube
Rubik's Cube
Rubik's Cube is a 3-D mechanical puzzle invented in 1974 by Hungarian sculptor and professor of architecture Ernő Rubik.Originally called the "Magic Cube", the puzzle was licensed by Rubik to be sold by Ideal Toy Corp. in 1980 and won the German Game of the Year special award for Best Puzzle that...
World Championships held in Budapest
Budapest
Budapest is the capital of Hungary. As the largest city of Hungary, it is the country's principal political, cultural, commercial, industrial, and transportation centre. In 2011, Budapest had 1,733,685 inhabitants, down from its 1989 peak of 2,113,645 due to suburbanization. The Budapest Commuter...
, Hungary
Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...
. He later published his unique method, known as the Petrus system, on the Internet. It has become an extremely popular method among intermediate and upper-level speed cubers, although its more recent usage has diminished considerably at the professional level due to the increased predominance of brute force algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
-based methods. Petrus won the 3x3x3 Fewest Moves category at the 2005 World Championships held November, 2005 at Lake Buena Vista, Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, claiming the $500 purse. He currently resides in Silicon Valley
Silicon Valley
Silicon Valley is a term which refers to the southern part of the San Francisco Bay Area in Northern California in the United States. The region is home to many of the world's largest technology corporations...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. Lars Petrus is currently taking time off from employment at Google
Google
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
.
The Lars Petrus System
The Petrus System was designed as an alternative to the popular layer-based solutions of the early 1980s. Petrus reasoned that as you construct layers, further organization of the cube's remaining pieces is restricted by what you have already done. In order for a layer-based solution to continue after the first layer had been constructed, the solved portion of the cube would have to be temporarily disassembled while the desired moves were made, then reassembled afterward. Petrus sought to get around this quagmire by solving the cube outwards from one corner, leaving him with unrestricted movement on several sides of the cube as he progressed. This method is often used to solve the cube in a fewest-moves solution.The Method
The system uses seven basic steps to solve a Rubik's Cube.- Build a 2x2x2 corner
- Expand to a 2x2x3 without destroying the 2x2x2 block
- Correct edge orientation
- Solve two complete layers
- Permute the remaining corners
- Orient the remaining corners
- Permute the final edges
Petrus invented three simple and flexible algorithms to complete the last three steps, which he named Niklas, Sune, and Allan.
While the method stands alone as an efficient system for solving the Rubik's Cube, many modifications have been made over the years to stay on the cutting edge of competitive speedcubing
Speedcubing
Speedcubing is the activity of solving a Rubik's Cube or related puzzle as quickly as possible...
. Many more algorithms have been added to shave seconds off the solution time, and steps 5+6 or 6+7 are often combined depending on the problems each case presents. Petrus' personal best speedsolve is 13.60 seconds, achieved in 2006.
External links
- Rubik's World Championship 2005 - Official Results
- Solving Rubik's Cube for Speed by Lars Petrus
- Lars's Official Records - From the World Cube AssociationWorld Cube AssociationThe World Cube Association is an organization that regulates and holds Rubik's Cube competitions. It was founded by Ron van Bruchem of the Netherlands and Tyson Mao of the United States...
website