History
The earliest known reference to the Knight's Tour problem dates back to the 9th century AD. In Rudraṭa's Kavyalankara (5.15), a Sanskrit work on Poetics, the pattern of a knight's tour on a half-board has been presented as an elaborate poetic figure ("citra-alaṅkāra") called the "turagapadabandha" or 'arrangement in the steps of a horse.' The same verse in four lines of eight syllables each can be read from left to right or by following the path of the knight on tour. Since the Indic writing systems used for Sanskrit are syllabic, each syllable can be thought of as representing a square on a chess board. Rudrata's example is as follows:
से ना ली ली ली ना ना ना ली
ली ना ना ना ना ली ली ली ली
न ली ना ली ली ले ना ली ना
ली ली ली ना ना ना ना ना ली
se nā lī lī lī nā nā lī
lī nā nā nā nā lī lī lī
na lī nā lī le nā lī nā
lī lī lī nā nā nā nā lī
For example, the first line can be read from left to right or by moving from the first square to second line, third syllable (2.3) and then to 1.5 to 2.7 to 4.8 to 3.6 to 4.4 to 3.2.
One of the first mathematicians to investigate the knight's tour was Leonhard Euler. The first procedure for completing the Knight's Tour was Warnsdorff's rule, first described in 1823 by H. C. von Warnsdorff.
In the 20th century, the Oulipo group of writers used it among many others. The most notable example is the 10 × 10 Knight's Tour which sets the order of the chapters in Georges Perec's novel Life: A User's Manual. The sixth game of the 2010 World Chess Championship between Viswanathan Anand and Veselin Topalov saw Anand making 13 consecutive knight moves (albeit using both knights) -– online commentors jested that Anand was trying to solve the Knight's Tour problem during the game.
Read more about this topic: Knight's Tour
Famous quotes containing the word history:
“No matter how vital experience might be while you lived it, no sooner was it ended and dead than it became as lifeless as the piles of dry dust in a school history book.”
—Ellen Glasgow (1874–1945)
“They are a sort of post-house,where the Fates
Change horses, making history change its tune,
Then spur away o’er empires and o’er states,
Leaving at last not much besides chronology,
Excepting the post-obits of theology.”
—George Gordon Noel Byron (1788–1824)
“All history attests that man has subjected woman to his will, used her as a means to promote his selfish gratification, to minister to his sensual pleasures, to be instrumental in promoting his comfort; but never has he desired to elevate her to that rank she was created to fill. He has done all he could to debase and enslave her mind; and now he looks triumphantly on the ruin he has wrought, and say, the being he has thus deeply injured is his inferior.”
—Sarah M. Grimke (1792–1873)