Sources page biographical material

5.A.1. NON SQUARE PIECES
S&B, pp. 130 133, show many versions.

See Kinsey, 1878, above, for mention of triangular and diamond shaped pieces.

Henry Walton. US Patent 516,035 -- Puzzle. Applied: 14 Mar 1893; patented: 6 Mar 1894. 1p + 1p diagrams. Described in Hordern, pp. 27 & 68 69, C1. 4 x 4 area with five 1 x 2 & two 2 x 1 pieces.

Lorman P. Shriver. US Patent 526,544 -- Puzzle. Applied: 28 Jun 1894; patented: 25 Sep 1894, 2pp + 1p diagrams. Described in Hordern, p. 27. 4 x 5 area with two 2 x 1 & 15  1 x 1 pieces. Because there is only one vacant space, the rectangles can only move lengthwise and so this is a dull puzzle.

Frank E. Moss. US Patent 668,386 -- Puzzle. Applied: 8 Jun 1900; patented: 19 Feb 1901. 2pp + 1p diagrams. Described in Hordern, pp. 27 28 & 75, C14. 4 x 4 area with six 1 x 1, two 1 x 2 & two  2 x 1 pieces, allowing sideways movement of the rectangles.

William H. E. Wehner. US Patent 771,514 -- Game Apparatus. Applied: 15 Feb 1904; patented: 4 Oct 1904. 2pp + 1p diagrams. First to use L-shaped pieces. Described in Hordern, pp. 28 & 107, D5.

Lewis W. Hardy. US Patent 1,017,752 -- Puzzle. Applied: 14 Dec 1907; patented: 20 Feb 1912. 3pp + 1p diagrams. Described in Hordern, pp. 29 & 89 90, C43-45. 4 x 5 area with one 2 x 2, two 1 x 2, three 2 x 1 & four 1 x 1 pieces.

L. W. Hardy. Pennant Puzzle. Copyright 1909. Made by OK Novelty Co., Chicago. No known patent. Described in Gardner, SA (Feb 1964) = 6th Book, chap. 7 and in Hordern, pp. 28 29 & 78-79, C19. 4 x 5 area with one  2 x 2, two 1 x 2, four 2 x 1, two  1 x 1 pieces.

Nob Yoshigahara designed Rush Hour in the late 1970s and it was produced in Japan as Tokyo Parking Lot. Binary Arts introduced it to the US in 1996 and it became very popular.

Winning Ways. 1982. Pp. 769-777: A trio of sliding block puzzles. This covers Dad's Puzzler (c19, with piece 8 moved two places to the right), The Donkey (C27d, with all the central pieces moved down one position) and The Century (C42), showing how one can examine partial problems which allow one to consider many positions the same and much reduce the number of positions to be studied. This allows the graph to be written on a large sheet and solutions to be readily found.

Andrew N. Walker. Checkmate and other sliding-block puzzles. Mathematics Preprint Series, University of Nottingham, no. 95-32, 1995, 8pp + covers. Describes a version by W. G. H. [Wil] Strijbos made by Pussycat. 4 x 4 with an extra position below the left column. Pieces are alternately black and white and have a black king, a white king and a white rook on them and the object is to produce checkmate, but all positions must be legal in chess, except that the black and white markings do not have to be correct in the intermediate positions. However, one soon finds that one tile is fixed in place and two other tiles are joined together. He discusses general computer solving techniques and finds there are five optimal solutions in 68 moves. He then discusses other problems, citing Winning Ways, Hordern and my Sliding Block Puzzle Circulars. He gives the UNIX shell scripts that he used.

Ivars Peterson. Simple puzzles can give computers an unexpectedly strenuous workout. Science News 162:7 (17 Aug 2002) 6pp PO from their website, http:''sciencenews.org . Reports on recent work by Gary W. Flake & Eric B. Baum that Nob Yoshigahara's Rush Hour puzzle is PSPACE complete, but is not polynomial time. Robert A. Hearn and Erik D. Demaine have verified and extended this, showing other sliding block puzzles are PSPACE complete, including the case where all pieces are dominoes and can slide sideways as well as front and back.