Showing posts with label magic. Show all posts
Showing posts with label magic. Show all posts

Tuesday, 10 March 2020

Magic Knight Tours 8x10 and 8x14

On my 80th Birthday, and shortly after, I was sent a series of 80-cell magic knight tours on the 8x10 rectangle by Guenter Stertenbrink and later some by Awani Kumar. 

Some of the tours in the Stertenbrink list are closed tours with a complete braid along the bottom border. This can be extended, in four different ways, to cover a further four rows forming a magic 8x14 tour. Here is one example that I sent to these correspondents on 18 February.

These tours answer the final missing cases of Magic Knight Tours on rectangular boards.

07 62 07 52 09 56 01 58
06 51 06 61 04 59 10 55
49 08 63 08 53 12 57 02
64 05 50 05 60 03 54 11
09 48 65 04 27 30 83 86
02 67 46 11 82 85 28 31
47 10 03 66 29 26 87 84
68 01 12 45 88 81 32 25
13 44 99 70 23 34 89 80
00 69 14 43 90 79 24 33
41 16 71 98 35 22 77 92
72 97 42 15 78 91 36 21
17 40 95 74 19 38 93 76
96 73 18 39 94 75 20 37

Underlined: add 100.

The formations on the fifth to eighth ranks down are familiar: a double Beverley quad, and a Snake-head formation as in the 12x12 magic tour by the Rajah of Mysore.

I am not able to do geometrical diagrams as yet on my new computer, but have made some progress with installing HTML-Kit and Cute-FTP which will enable me to update some of the pages on my website. I have already begun to update the History section, where a lot of the links no longer work, but have not yet uploaded this work to the website. .

Next Weekend 13 -15 March I am due to play in the Blackpool Chess Congress, though I've been having doubts whether to go in view of the Coronavirus outbreak.


Monday, 25 April 2011

Magic Rook Tours

The image shows three diagonally magic rook tours that I constructed on 20-21 May 1986 but then seem to have forgotten about. (It was a busy year for me!) The tours have biaxial symmetry and each quarter tour is a bisatin (i.e. uses two cells in each rank and file). If the numbering is shifted by one quarter, so 17 becomes 1, 18 becomes 2 and so on, the rank and file magic property is automatically retained. However for the diagonals to remain magic there must be two numbers less than or equal to 16 in each (i.e. the bisatin has to be diagonal as well). The work was inspired by a less structured diagonally magic rook tour by J. Brugge that appeared in the German chess problem magazine Die Schwalbe in August 1985. Anyone care to enumerate all the diagonal bisatins that could be used?