With players from 68 countries and ...
By Rob Van Zeijst
With players from 68 countries and territories participating, the 27th World Amateur Go Championship will be held in Sasebo, Nagasaki Prefecture, from Sunday to Wednesday. Prior to the event, a number of activities will be held, including the Nagasaki Children Igo Festival and the Nagasaki Pair Go Festival on Saturday afternoon. Although this tournament brings together the world's strongest amateur go players, it comes as a shock to see that the representatives from China, Hong Kong, Taiwan and South Korea are, respectively, 13, 13, 16 and 18 years old. For comparison, Japan's representative, two-time world amateur champion Satoshi Hiraoka, is 35 years old. The difference in age says it all. In Japan, go has an image as a game for older people. On the other hand, the other top go powers in Asia have improved fast because of the innovations brought by the younger generation, particularly teenagers. For more information, including results, please go to: http://www.nihonkiin.or.jp/amakisen/worldama/27/index-e.htm.
Applying the ko rule
Last week, we discussed the ko rule, which prevents a situation from recurring. This was the last rule of this 4,000-year-old game. Let us review this rule and let us look at some strategy and tactics that accompany it.
Diagram 1: The marked stone is in atari, i.e. it is down to one liberty. Therefore, Black can capture it by playing at 1.
Diagram 2: This is the new situation. As you can see, Black's marked stone is in atari. However, the ko rule says, a board position cannot be repeated. Therefore, White cannot capture the marked stone by playing at A.
Diagram 3: Now imagine this situation. After black 1, White threatens to cut off the three marked black stones with 2. Black can connect with 3, but that means the board position has changed. In other words, White can now capture black 1 with 4. We refer to white 2 as a ko threat. Often ko threats are answered but not always.
Diagram 4: Let us now look at a full-board situation in which a ko is all-important. You can see that if Black connects his marked stone at 2, White would play at 1 followed by Black blocking at A. Black will have 11 points in territory against White 12. In other words, if he connects his marked stone, Black therefore loses the game. However, Black can avoid this and score an even number of points by playing at 1. White will capture with 2, but by carefully playing his ko threats, Black can outlast White in the ko fight.
Diagram 5 (white 8 is not shown): Black captures the marked white stone with 5. White then plays a ko threat with 6, which is answered by black 7. Since the board situation has changed again, White can now play at 8 (where the marked stone is). Black must now make a ko threat at 9, which will be answered by White 10.
Diagram 6 (white 14, black 17 and white 20 are not shown): Black captures the ko again with 11. White makes a ko threat at 12, and Black must reply with 13. White 14 (not shown) captures the ko. Again, it is Black's turn to make a ko threat. Black 15 must be answered by white 16. Black 17 (not shown) captures the ko again. White 18 is answered by 19. Once again, White captures the ko with 20 (not shown).
Diagram 7 (Black 25 is not shown): Black plays his last ko threat at 21. White must defend with 22. Black captures the ko with 23 but White now has no ko threat and must pass. Black can then connect with 25 at the spot where the marked white stone was taken. Now count again. After removing all the dead stones, you will find Black has 9 points in territory while he captured 3 stones plus 4 in the ko, a total of 16 points. White has 8 points in territory, captured 4 stones plus 4 in the ko, which also works out to 16 points. Therefore, the score is even and Black has avoided a loss. Incidentally, in go a draw is called "igo."
Conclusion: Although the ko itself was worth only one point, it is decisive for the outcome of the game. In this case, Black had one more threat than White and consequently decided the ko in his favor. In the majority of cases, ko battles hinge on the number of ko threats each player has. However, sometimes the value of the ko is so great any ko threat is ignored. We will look at such a ko next week.
Van Zeijst is a four-time European go champion and European representative at the Fujitsu World Championship.