Sources page biographical material

5. COMBINATORIAL RECREATIONS
7.AZ is actually combinatorial rather than arithmetical and I may shift it.
5.A. THE 15 PUZZLE, ETC.
Pictorial versions: The Premier (1880), Lemon (1890), Stein (1898), King (1927).

Double-sided versions: The Premier (1880), Brown (1891).

Relation to Magic Squares: Loyd (1896), Cremer (1880), Tissandier (1880 & 1880?), Cassell's (1881), Hutchison (1891).

Making a magic square with the Fifteen Puzzle: Dudeney (1898), Anon & Dudeney (1899), Loyd (1914), Dudeney (1917), Gordon (1988). See also:  Ollerenshaw & Bondi in 7.N.

GENERAL
Peter Hajek. 1995 report of his 1992 visit to the Museum of Money, Montevideo, Uruguay, with later pictures by Jaime Poniachik. In this Museum is a metal chest made in England in 1870 for the National State Bank of Uruguay. The front has a 7 x 7 array of metal squares with bolt heads. These have to be slid in a 12 move sequence to reveal the three keyholes for opening the chest. This opens up a whole new possible background for the 15 Puzzle -- can anyone provide details of other such sliding devices?
S&B, pp. 126 129, shows several versions of the puzzle.

L. Edward Hordern. Sliding Piece Puzzles. OUP, 1986. Chap. 2: History of the sliding block puzzle, pp. 18 30. This is the most extensive survey of the history. He concludes that Loyd did not invent the general puzzle where the 15 pieces are placed at random, which became popular in 1879(?). Loyd may have invented the 14 15 version or he may have offered the $1000 prize for it, but there is no evidence of when (1881??) or where. However, see the entries for Loyd's Tit Bits article and Dudeney's 1904 article which seem to add weight to Loyd's claims. Most of the puzzles considered here are described by Hordern and have code numbers beginning with a letter, e.g. E23, which I will give.

I contributed a note about computer techniques of solving such puzzles and hoping that programmers would attack them as computer power increased.

In 1993-1995, I produced four Sliding Block Puzzle Circulars, totalling 24 pages (since reformatted to 21), largely devoted to reporting on computer solutions of puzzles in Hordern. Since then, a large number of solution programs have appeared and many more puzzles have appeared. The best place to look is on Nick Baxter's Sliding Block Home Page: http://www.johnrausch.com/slidingblockpuzzles/index.html .