The Checker Maven

Double Cross in the Double Cross

A few years ago, Ed Gilbert, the author of the KingsRow computer checkers engine, and the creator of the companion 10-piece endgame database, sent some new play to one of checker's sharpest-eyed analysts, Brian Hinkle. Ed told Brian the following:

"The 5-9 24-20 Double Cross is indeed a draw. This is exciting news to me, since this is a new, unknown draw in a ballot that is generally considered by a lot of players to be the most difficult of the 3-move tournament ballots. This morning I loaded the new opening book into Kingsrow and played along the PV. It dropped out of book at the 40th ply into a very interesting position where White had sacrificed a man to gain a first king with a positional advantage."

Ed showed the following line of play:

1. 9-14 23-18
2. 14x23 27x18
3. 5-9 24-20
4. 10-15 28-24
5. 7-10 21-17
6. 3-7 17-13
7. 9-14 18x9
8. 15-18 22x15
9. 10x28 9-5
10. 11-16 20x11
11. 8x15 31-27---A
12. 4-8 25-22
13. 8-11 29-25
14. 11-16 25-21
15. 16-20 21-17
16. 7-11 27-23
17. 12-16 13-9
18. 6x13 17-14
19. 2-6 14-9
20. 6-10 9-6---B

A---25-22 4-8 31-27 same.

B---This is the end of the computer's opening book moves. Note that Ed constructed a special opening book that examined the Double Cross in great depth and detail.

Ed comments further, "Every black move from 24-20 up to move 13 is forced."

Here is the position at the end of the KingsRow specialized Double Cross opening book.


Black to Play and Draw


Finding the rest of the solution is not an easy task, but you owe it to yourself to give it a try. The solution is not long, but it is very surprising, perhaps ranking among the most surprising things we've ever seen on the checkerboard. After you've done your analysis, click on Read More to see the truly stunning conclusion.


21. 15-19 6-2
22. 10-15 2-7
23. 20-24 30-25
24. 24-27 25-21
25. 27-31 23-18
26. 31-27 32x23
27. 28-32 7-10
28. 32-27 10-7
29. 27-32 7-10

Here's the final position:


Black to Play; Drawn


Ed says of this incredible line of play, " I had thought that fortresses were only possible in contrived positions, but here is one in a PV line of the Double Cross."

The game of checkers never ceases to amaze, entertain, and at times astound us.

The Checker Maven thanks Ed Gilbert for his assistance in the preparation of this column.

KingsRow Author Ed Gilbert
(Photo by Carol Gilbert)

01/29/11 - Category: Programs -Printer friendly version-
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