French
French (french: français(e), link=no) may refer to:
* Something of, from, or related to France
** French language, which originated in France, and its various dialects and accents
** French people, a nation and ethnic group identified with Franc ...
for "time-waster"), also known as the Chinese rings, Cardan's suspension, Cardano's rings, Devil's needle or five pillars puzzle, is a
disentanglement puzzle
Disentanglement puzzles (also called entanglement puzzles, tanglement puzzles, tavern puzzles or topological puzzles) are a type or group of mechanical puzzle that involves disentangling one piece or set of pieces from another piece or set of piec ...
featuring a loop which must be disentangled from a sequence of rings on interlinked pillars. The loop can be either string or a rigid structure.
It is thought to have been
invent
An invention is a unique or novel device, method, composition, idea or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It may also be an entirely new concept. If an ...
ed originally in
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
. The origins are obscure. The American ethnographer
Stewart Culin
Stewart Culin (July 13, 1858 – April 8, 1929) was an American ethnographer and author interested in games, art and dress. Culin played a major role in the development of ethnography, first concentrating his efforts on studying the Asian-Ameri ...
related a tradition attributing the puzzle's invention to the 2nd/3rd century Chinese general
Zhuge Liang
Zhuge Liang ( zh, t=諸葛亮 / 诸葛亮) (181 – September 234), courtesy name Kongming, was a Chinese statesman and military strategist. He was chancellor and later regent of the state of Shu Han during the Three Kingdoms period. He is r ...
. It was used by French peasants as a locking mechanism.
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.
Mathematical solution
The 19th-century French mathematician
Édouard Lucas
__NOTOC__
François Édouard Anatole Lucas (; 4 April 1842 – 3 October 1891) was a French mathematician. Lucas is known for his study of the Fibonacci sequence. The related Lucas sequences and Lucas numbers are named after him.
Biography
Lucas ...
, the inventor of the
Tower of Hanoi
The Tower of Hanoi (also called The problem of Benares Temple or Tower of Brahma or Lucas' Tower and sometimes pluralized as Towers, or simply pyramid puzzle) is a mathematical game or puzzle consisting of three rods and a number of disks of va ...
puzzle, was known to have come up with an elegant solution which used
binary
Binary may refer to:
Science and technology Mathematics
* Binary number, a representation of numbers using only two digits (0 and 1)
* Binary function, a function that takes two arguments
* Binary operation, a mathematical operation that t ...
and
Gray codes
The reflected binary code (RBC), also known as reflected binary (RB) or Gray code after Frank Gray, is an ordering of the binary numeral system such that two successive values differ in only one bit (binary digit).
For example, the representat ...
, in the same way that his puzzle can be solved. The minimum number of moves to solve an ''n''-ringed problem has been found to be
:
For other formulae, see .
See also
*
ABACABA pattern
The ABACABA pattern is a recursive fractal pattern that shows up in many places in the real world (such as in geometry, art, music, poetry, number systems, literature and higher dimensions). Patterns often show a DABACABA type subset. ''AA'', ...
*
Disentanglement puzzle
Disentanglement puzzles (also called entanglement puzzles, tanglement puzzles, tavern puzzles or topological puzzles) are a type or group of mechanical puzzle that involves disentangling one piece or set of pieces from another piece or set of piec ...
*
Towers of Hanoi
The Tower of Hanoi (also called The problem of Benares Temple or Tower of Brahma or Lucas' Tower and sometimes pluralized as Towers, or simply pyramid puzzle) is a mathematical game or puzzle consisting of three rods and a number of disks of va ...