Rubik Cubes For Geeks

At look at different unscrambling algorithms. From layer-by-layer approach to mathematics. This slides were presented at Barcamp Singapore 2009.

Transcript

1. Rubik Cubes For Geeks http://bit.ly/rubikcube Barcamp Singapore 4 21st Nov 2009 By Benson & Hong (CC) BY
2. Overview •Origin •Structure •Notations •Techniques •Speed Cubing •Competition
3. Once Upon A Time... •Erno Rubik •Professor of Architecture •Invented in 1974 •Original color scheme (White, Yellow, Red, Orange, Blue, Green)
4. Structure •6 faces •8 corners (3 colors) •12 edges (2 colors) •6 + 8 + 12 = 26 cublets •6 springs pulling the 6 centre cublets
5. Speak The Language •R - Right face clockwise •L - Left face clockwise •U - Upper face clockwise •D - Down face clockwise •F - Front face clockwise •B - Back face clockwise •R' - Right face anti-clockwise •F' - Front face anti-clockwise •B2 - Back face 180 degree •U2 - Upper face 180 degree
6. Techniques •Layer-By-Layer ◦Most popular ◦E.g.Toy R' Us booklet, Fridrich •Block Building ◦E.g. Lars Petrus, Roux •Corner First ◦E.g. Waterman •Mathematical ◦Rubik's Cubic Compendium (Recreations in Mathematics)
7. Need For Speed •Look ahead •Finger tricks •Lubing
8. Lube Your Cube •Bad ◦Methylene Chloride ◦Acetone ◦WD-40 (good sticker remover) •Good ◦Silicon spray
9. Competition •World Cube Association (http://www.worldcubeassociation. org) •Rules and Regulations •Judges, scramblers, score takers •Speed cubing, single hand, blindfold, feet cubing, ... •"Competitors must bring and use their own puzzles. Competitors may borrow puzzles from other competitors..." •Max. 15s inspection
10. DEMO
11. Fridrich Method 1. Bottom Cross 2. F2L (First 2 Layers) = 4 x (corner + edge) 3. OLL (Orientation of Last Layer) + PLL (Permutation of Last Layer) •Characteristics ◦Popular! ◦Need memorization ◦Many variations for last layer
12. Lars Petrus Method 1. 2 x 2 x 2 2. 2 x 2 x 3 3. Fix bad edges 4. Finish first 2 layers 5. Positions corners 6. Twist the corners 7. Position the edges Characteristics: • Freedom in movement • Less "breaking" of what you have done • Fewer moves (3x3x3 Fewest Moves Category 2005 World Championship)