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Lars Erik "Larry" Petrus (born 4 november 1960 in Luleå in Sweden) is an accomplished speedcuber. In 1982, 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 method, known as the Petrus system, on the Internet. It became a fairly popular method among intermediate and upper-level speedcubers, although its more recent use has diminished considerably due to the increased predominance of methods such as ZZ, Roux, and CFOP. Petrus won the 3x3x3 Fewest Moves category at the 2005 World Championships held in November 2005 at Lake Buena Vista, Florida, USA claiming the US$500 prize. He currently (since 1995) resides in SF Bay Area, California, USA. The Lars Petrus System[edit] The Petrus System was designed as an alternative to the popular layer-based solutions of the early 1980s. Petrus reasoned that as a solver constructs layers, further organization of the cube's remaining pieces is restricted by what one has 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[edit] The system uses seven basic steps to solve a Rubik's Cube.

Build a 2x2 block 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. 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 13.6 seconds, achieved in 2006. External links[edit]

Rubik's World Championship 2005 - Official Results Solving Rubik's Cube for Speed by Lars Petrus Lars's Official Records - From the World Cube Association website

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Rubik's Cube

Puzzle inventors

Ernő Rubik Uwe Mèffert Tony Fisher Panagiotis Verdes Oskar van Deventer

Rubik's Cubes

Overview 2×2×2 (Pocket Cube) 3×3×3 (Rubik's Cube) 4×4×4 (Rubik's Revenge) 5×5×5 (Professor's Cube) 6×6×6 (V-Cube 6) 7×7×7 (V-Cube 7) 8×8×8 (V-Cube 8)

Cubic variations

Helicopter Cube Skewb Square 1 Sudoku Cube Nine-Colour Cube Void Cube

Non-cubic variations

Tetrahedron

Pyraminx Pyraminx Duo Pyramorphix BrainTwist

Octahedron

Skewb Diamond

Dodecahedron

Megaminx (Variations) Pyraminx Crystal Skewb Ultimate

Icosahedron

Impossiball Dogic

Great dodecahedron

Alexander's Star

Truncated icosahedron

Tuttminx

Cuboid

Floppy Cube (1x3x3) Rubik's Domino (2x3x3)

Virtual variations (>3D)

MagicCube4D MagicCube5D MagicCube7D Magic 120-cell

Derivatives

Missing Link Rubik's 360 Rubik's Clock Rubik's Magic

Master Edition

Rubik's Revolution Rubik's Snake Rubik's Triamid

Renowned solvers

Erik Akkersdijk Yu Nakajima Bob Burton, Jr. Jessica Fridrich Chris Hardwick Kevin Hays Rowe Hessler Leyan Lo Shotaro Makisumi Toby Mao Tyson Mao Frank Morris Lars Petrus Gilles Roux David Singmaster Ron van Bruchem Eric Limeback Anthony Michael Brooks Mats Valk Feliks Zemdegs Collin Burns Lucas Etter Max Park

Solutions

Speedsolving

Speedcubing

Methods

Layer by Layer CFOP Method Roux Method Corners First Optimal

Mathematics

God's algorithm Superflip Thistlethwaite's algorithm Rubik's Cube group

Official organization

World Cube Association

Related articles

Rubik's Cube in popular culture The Simple Solution to Rubik's Cube 1982 World Rubik's Cube