Gert Wilts, 19 Mar 1995
In the book "Histoires extraordinaires" from Jean Bertin, France, there is an example of RA in the game of draught (checkers). Unfortunately I don't have the book at hand so that I cannot copy this example.
The following is an example of RA in the game of checkers, taken from the book "Histoires extraordinaires sur 64 cases" from Jean Bertin, France.
+----------+ + + + + + b b + + B + <--- How could this pawn have reached its square? + b b + + + + B + + + + + + B B + +----------+ Black to move.
I don't know the rules of checkers. Can anybody tell me if this is an interesting example of RA?
The position posted for the retro's checkers problem by Jean Bertin was:
White: c4,d1,f1,f7; Black:e6,e8,g6,g8 (On a 10x10 board) Black to move, explain how the checker on f7 got there.
I fiddled with this for a while (at first I didn't realize that the board was supposed to be 10x10 having missed the previous post in which a diagram was presented)
There are many different sets of rules for checkers, so the first problem is figuring out exactly which game we are talking about here.
Unfortunately, all of the versions I know of that are played on a 10x10 board are also played entirely on the dark squares of the checker-board, but all the peices in position given are on the light squares.
By what rules are we playing?
(If you don't know could you please Email me the solution, Gerd, if the book includes it?)
I haven't found the solution to the problem yet. I assume the American rules for checkers are used (no capture backwards, marjority capture isn't obligatory and promoted piece (king? I don't know the term in English) moves only 1 square also. The board is at least 8*8 (It came out of a book with '64' in the title.
If capturing backwards is allowed, the problem is easy : W e6,d5,a2,d1,f1 B e8,g8,g6,c4,b3 e6-f7 c4*f6 a2*c2
I would like to clarify some things:
Indeed the board used for this retro is a 10x10 board, and the position is:
The book doesn't give the author of this problem, but the author seems not to be Jean Bertin. I don't know what set of rules is used for this problem. The french text just states that it is the "jeu de Dames"; I assume that this must be the game of draughts. The book gives the following solution:
Intermediate position:
White: e1, f6, g1, g5, i1; Black: d6, d8, f8, i3, i5.
Then: 1. 50-45, (30-34); 2. 23-18, (34x23); (le moins mauvais) 3. 45x34 gagne"
Ah... The problem that I had encountered with the problem is that the position given has been mirror-imaged. The one posted was:
White: c4, d1, f1, f7 Black:e6, e8, g6, g8
What that should be is:
White: e1, e7, g1, h4 Black: d6, d8, f6, f8
The game being considered is "International Checkers" in which unpromoted pieces must move forward and digonally one square when not capturing and jump enemy peices diagonally either forward or backward when capturing. You are obliged to make a capture if you can and to continue jumping with that piece until it cannot do so (i.e. if you make a jump to a square where the piece you are moving can make another jump, it is mandatory to do so.)
Queens (or Dames) move like chess bishops and capture by making a bishop move over the square on which the enemy man is standing (continuing any number of spaces beyond) The enforced capture rule applies to them as well.
With that finally cleared up, the soluion posted, translated into algebraic notation for those who do not play checkers is:
White: e1, f6, g1, g5, i1; Black: d6, d8, f8, i3, i5
1: i1-j2 i5-h4 2: f6-e7 h4xf6 3: j2xh4
Gerd had asked if this was a good example of retro-analysis. Actually, once you are clear about what game you are dealing with it's very simple. As I mentioned in a previous post to this list, I orignally began looking at this problem on the 8x8 board and invite you all to do this same. consider the analogous problem in "Anglo-American Checkers":
White: c1, c7, e1, f4; Black: b6, b8, d6, d8
Anglo-American Checkers is played on an 8x8 board, men move as in International Checkers, but may only capture forward. Kings (promoted men) move just as the unpromoted men do, but can both move and capture forawrds and backwards. (There is no need for king to enter into your solution though) Anyway, How did the about position come to pass?
Now a technical question: If I use the 8x8 Anglo-Checkers problem above, who do I list as the author, seeing as I actidentally discovered the problem while working on a corrupted version of the problem from Bertins book?