Discussion:
Knight's tour = magic square?
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George Cox
2003-06-28 16:22:05 UTC
Permalink
If we number consecutively the squares visited on a knight's tour, can a
magic square result?

Surely not. It would be asking too much.

GC
Prai Jei
2003-06-28 21:36:06 UTC
Permalink
Post by George Cox
If we number consecutively the squares visited on a knight's tour, can a
magic square result?
Surely not. It would be asking too much.
GC
Best I heard of is a "semimagic" square, the diagonals do not add up to the
magic constant (260 for the standard 8x8 board) although the two diagonals
together add up to 520, twice the magic constant.
George Cox
2003-06-29 14:19:26 UTC
Permalink
Post by Prai Jei
Post by George Cox
If we number consecutively the squares visited on a knight's tour, can a
magic square result?
Surely not. It would be asking too much.
GC
Best I heard of is a "semimagic" square, the diagonals do not add up to the
magic constant (260 for the standard 8x8 board) although the two diagonals
together add up to 520, twice the magic constant.
Discussed here http://mathworld.wolfram.com/MagicTour.html a good site.

GC
Prai Jei
2003-06-29 20:59:30 UTC
Permalink
Post by George Cox
[snip]
Best I heard of is a "semimagic" square, the diagonals do not add up to the
magic constant (260 for the standard 8x8 board) although the two diagonals
together add up to 520, twice the magic constant.
Discussed here http://mathworld.wolfram.com/MagicTour.html a good site.
Couldn't get in! Access from Freeserve has been blocked because somebody has
been bu--ering about causing multiple hits or something. Help!
Odysseus
2003-06-29 23:27:55 UTC
Permalink
Post by Prai Jei
Post by George Cox
Discussed here http://mathworld.wolfram.com/MagicTour.html a good site.
Couldn't get in! Access from Freeserve has been blocked because somebody has
been bu--ering about causing multiple hits or something. Help!
Here's the text at least -- I won't attempt to reproduce, or even
describe, the figures!

[quotation begins]
============================================

Let a chess piece make a tour on an n*n chessboard whose squares are
numbered from 1 to n^2 along the path of the chess piece. Then the
tour is called a magic tour if the resulting arrangement of numbers
is a magic square, and a semimagic tour if the resulting arrangement
of numbers is a semimagic square. If the first and last squares
traversed are connected by a move, the tour is said to be closed (or
"re-entrant"); otherwise it is open. (Note some care with terminology
is necessary. For example, Jelliss terms a semimagic tour a "magic
tour" and a magic tour a "diagonally magic tour.")

[3 diagrams]

Magic knight's tours are not possible on n*n boards for n odd. They
are possible for all boards of size 4k*4k for k > 3, but are believed
to be impossible for n = 8. Beverley (1848) composed the 8*8
semimagic knight's tour (left figure). Another semimagic tour for n =
8 with main diagonal sums of 348 and 168 was found by de Jaenisch
(1862; Ball and Coxeter 1987, p. 185; center figure). The "most
magic" knight's tour known on the 8*8 board has main diagonal sums of
264 and 256 and is shown on the right (Francony 1882). Extensive
histories of knight's magic tours are given by Murray (1951) and Jelliss.

[diagram]

Combining two half-knights' tours one above the other as in the above
right figure does, however, give a magic square (Ball and Coxeter
1987, p. 185).

[diagram]

The illustration above shows a closed magic knight's tour on a 16*16
board (Madachy 1979, p. 88).

[diagram]

A magic tour for king moves is illustrated above (Coxeter 1987, p. 186).

See also:
Chessboard <http://mathworld.wolfram.com/Chessboard.html>,
Knight's Tour <http://mathworld.wolfram.com/KnightsTour.html>,
Magic Square <http://mathworld.wolfram.com/MagicSquare.html>,
Semimagic Square <http://mathworld.wolfram.com/SemimagicSquare.html>,
Tour <http://mathworld.wolfram.com/Tour.html>

--------------------------------------------

References:

Ball, W. W. R. and Coxeter, H. S. M. Mathematical Recreations and Essays
<http://www.amazon.com/exec/obidos/ASIN/0486253570/weisstein-20>,
13th ed. New York: Dover, pp. 185-187, 1987.

Beverly, W. Philos. Mag. p. 102, Apr. 1848.

de Jaenisch, C. F. Chess Monthly. 1859.

de Jaenisch, C. F. Traite des Applications de l'Analyse Mathematiques
au jeu des Echecs. Leningrad, 1862.

Francony. In Le Siécle 1876-1885. (Ed. M. A. Feisthamel). 1882.

Jelliss, G. "Knight's Tour Notes."
<http://home.freeuk.net/ktn/>.

Jelliss, G. "General Theory of Magic Knight's Tours."
<http://home.freeuk.net/ktn/mg.htm>.

Kraitchik, M. l'Echiquier. 1926.

Madachy, J. S. Madachy's Mathematical Recreations
<http://www.amazon.com/exec/obidos/ASIN/0486237621/weisstein-20>. New
York: Dover, pp. 87-89, 1979.

Marlow, T. W. The Problemist. Jan. 1988.

Murray, H. J. R. The Magic Knight's Tours, a Mathematical Recreation. 1951.

Roberts, T. S. The Games and Problems J. Jan. 2003.

Wenzelides, C. Schachzeitung, p. 247, 1849.

Author: Eric W. Weisstein
© 1999 CRC Press LLC, © 1999-2003 Wolfram Research, Inc.
<http://www.wolfram.com/>

============================================
[quotation ends]

I hope this constitutes "fair use"!

--Odysseus

George Cox
2003-06-29 14:18:58 UTC
Permalink
Post by George Cox
If we number consecutively the squares visited on a knight's tour, can a
magic square result?
Surely not. It would be asking too much.
GC
http://mathworld.wolfram.com/MagicTour.html
Alex
Thanks
GC
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