In order to ascertain if you have the move when it is your turn to play, add together all the men, both black and white, in one of the systems, taking no notice of those in the other system, and if the number is odd, you have the move. In Diagram No. 10, for instance, if you have the black men, and it is your turn to play, you will find three men on your own system, and therefore you have the move, and must win by playing 10-15. When White moves, there will again be an odd number of men on your system, and you will still have the move, and he must sacrifice both his men.
No. 10.
No. 11.
In Diagram No. 11, if you count up the men on either your own or your adversary’s system, you will find that the number is even, and as you have not the move you should force an exchange immediately, which will give it to you, and win the game.
Every single exchange of man for man changes the move when only one of the capturing pieces remains on the board, and the following rule is given for ascertaining how proposed exchanges in complicated positions will affect the move:—The capturing pieces of both black and white in both systems must first be added together, and if the number agrees—in the matter of being odd or even—with that of the number of captured pieces in each system, the move will not be changed; but if one number so found is odd, and the other is even, the move will be changed.
ILLUSTRATIVE GAMES.
The asterisk shows the losing move.
| Play with Black Men. | Play with White Men. | |||||
|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| 11-15 | 11-15 | 10-15 | 11-15 | 11-15 | 11-15 | 10-15 |
| 22 18 | 23 19 | 22 18 | 24 20 | 22 18 | 23 19 | 23 18 |
| 15-22 | 8-11 | 15-22 | 8-11 | 15-22 | 8-11 | 12-16 |
| 25 18 | 22 17 | 25 18 | 28 24 | 25 18 | 26 23 | 21 17 |
| 8-11 | 3- 8 | 6-10 | 4- 8 | 8-11 | 4- 8 | 16-19 |
| 29 25 | *17 14 | 29 25 | 23 19 | 29 25 | 30 26 | 17 14 |
| 4- 8 | 9-18 | 10-15 | * 9-13 | 4- 8 | * 9-13 | 9-13 |
| 24 20 | 21 17 | *25 22 | 20 16 | 24 20 | 19 16 | 24 20 |
| 10-15 | 18-22 | 15-19 | 11-20 | 10-15 | 12-19 | 8-12 |
| 25 22 | 25 18 | 23 16 | 22 17 | 25 22 | 23 16 | 25 21 |
| 12-16 | 15-22 | 12-19 | 13-22 | * 9-13 | 11-20 | 12-16 |
| *27 24 | 26 23 | 24 15 | 25 4 | 20 16 | 22 17 | 21 17 |
| 15-19 | 5- 9 | 9-14 | W wins. | 12-19 | 13-22 | 4- 8 |
| 24 15 | 17 13 | 18 9 | 23 16 | 25 4 | 29 25 | |
| 16-19 | 11-15 | 11-25 | 11-20 | W wins. | 6- 9 | |
| 23 16 | 23 18 | B wins. | 18 4 | 27 24 | ||
| 9-14 | 1- 5 | W wins. | 1- 6 | |||
| 18 9 | 18 11 | 32 27 | ||||
| 11-25 | 7-23 | 6-10 | ||||
| 28 24 | 27 18 | 27 23 | ||||
| 5-14 | 9-14 | 8-12 | ||||
| 24 19 | 18 9 | 25 21 | ||||
| 6-10 | 5-14 | 2- 6 | ||||
| B wins. | B wins. | 31 27 | ||||
| 3- 8 | ||||||
| 30 25 | ||||||
| W wins. | ||||||