Baguenaudier

Baguenaudier (also known as the Chinese Rings, Cardan's Suspension, Cardano's Rings, Devil's needle or five pillars puzzle) is a mechanical puzzle featuring a double loop of string which must be disentangled from a sequence of rings on interlinked pillars. The puzzle is thought to have been invented originally in China. Stewart Culin provided that it was invented by the Chinese general Zhuge Liang in the 2nd century AD. The name "Baguenaudier", however, is French. In Italy they are called Anelli di Cardano (Cardano's Rings).

In fact, the earliest description of the puzzle in Chinese history was written by Yang Shen, a scholar in 16th century in his Dan Qian Zong Lu (Preface to General Collections of Studies on Lead).

Édouard Lucas, the inventor of the Tower of Hanoi puzzle, was known to have come up with an elegant solution which used binary and Gray codes, in the same way that his puzzle can be solved.

Variations of this include The Devil's Staircase, Devil's Halo and the Impossible Staircase. Another similar puzzle is the Giant's Causeway which uses a separate pillar with an embedded ring.

See also

• Disentanglement puzzle
• Towers of Hanoi

External links

• Weisstein, Eric W., "Baguenaudier" from MathWorld.
• Code solution
• The Devil's Halo listing at the Puzzle Museum
• David Darling – encyclopedia
• Photo