M Norton wrote:
Mariano Tomatis wrote:
26,534,728,821,064 the different potential knight's tour, the probability of using BY CHANCE the same closed path by Euler (as Plantard did) is 1 out of 26,534,728,821,064.
WE ALL KNOW THAT.
THERE IS NO REASON TO RAISE THAT FACT.
Mariano Tomatis does not want to discuss the variations - whereby the Knight Chess Piece starts from a different position and finishes in a different position on the chessboard.
Variation 1 - Found in Putnam and Wood's Book. The authors did not know Euler.
Variation 2 - Found in Vaincre 3, September 1989. Plantard never mentioned Euler.
Variation 3 - Found in Euler, "Solution d’une question curieuse qui ne paroit soumise à aucune analyse" (1766).
At least we agree on something: Plantard is a
variation of Euler's path. It would have been really stupid for him to use the same starting position!
That's why he did exactly what Euler suggested on the same paper.
Variation by rotating the chessboard:Eulero, “Solution d’une question curieuse qui ne paroit soumise à aucune analyse” in <i>Memoires de l'Academie Royale des Sciences et Belles Lettres</i> (1759) 15, Berlin: 1766, page 311 wrote:
3. [...] Il est évident, que cette route satisfait également, quand on veut commencer par quelqu'un de autres angles.
Variation by inversion of direction:Eulero, “Solution d’une question curieuse qui ne paroit soumise à aucune analyse” in <i>Memoires de l'Academie Royale des Sciences et Belles Lettres</i> (1759) 15, Berlin: 1766, page 311 wrote:
4. En retournant par la meme route on pourra aussi commencer par la case 64, & de là en passant successivement par les cases 63, 62, 61, &c. on parviendra enfin, après avoir parcouru toutes les cases, à celle du coin 1.
Variation by changing starting position:Eulero, “Solution d’une question curieuse qui ne paroit soumise à aucune analyse” in <i>Memoires de l'Academie Royale des Sciences et Belles Lettres</i> (1759) 15, Berlin: 1766, page 312 wrote:
6. [...] On pourra commencer par quelque case que ce soit, & de là continuer la course suivant l'ordre des nombres jusqu'à la case marquée par 64, d'où, en sauntant à la celle qui est marquée par 1, il acheveroit la course jusqu'à retourner à celle d'où il étoit parti.
These rules are so obvious that now they are present in any modern books about mathematical games. Who knows from which book Plantard got it? I don't. I just located the oldest closed path from which Plantard's tour was generated: the one by Euler. It would be really interesting to find an older author of the same closed path (or of one of its variations).
I never wrote that Plantard read Euler's text: it is an information which is absolutely useless which cannot be demonstered, being the same rules and the same path in tons of other more recent books.
Everything is available here:
http://www.renneslechateau.it/rennes-le-chateau.php?sezione=studi&id=greatparchment
See footnote #6.