Go teachers should offer advice and ...

By Rob Van Zeijst

Go teachers should offer advice and guidance to students rather than lecture them on the game. The best way to do this is to ask questions. This may slow down the pace of the lessons, but the students will benefit as they become more actively involved in the game and more likely to remember key points. An added bonus is that the students will learn to ask questions and think for themselves. As you bond with your students, more students will be attracted to your way of teaching and flock to your classes. Hopefully, the students will spread the game, but the ultimate aim of any teacher is to have students rise beyond the teacher's level.

Diagram 1: Sometime, perhaps within the first 10 games, the student will encounter a ko situation, like this one. Black 13 captures one stone (white 8), but has put himself in atari. What happens now?

Diagram 2: This is the result after Black has captured a stone at A. The marked stone appears to be in danger of being captured. However, this is where the ko rule kicks in. To ensure that there will always be progress on the go board, the ko rule prohibits a board position from being repeated. So if White plays at A to capture the marked black stone, we would get the same board position as the one before Black captured the white stone. Without the ko rule, Black and White would keep on capturing each other's stones in the ko, spelling a quick end to the excitement of the game.

Diagram 3: There is no need to explain the ko situation before the student asks about it. Once it occurs, ask him what rule he would devise to solve this situation. Many students come up with the correct solution. The ko rule states after the initial stone has been captured, the next move must be played elsewhere. So after Black's marked stone captured the white stone, White must play elsewhere before he can capture the marked stone by playing at A. However, after White plays elsewhere, there are a few possible scenarios. Black may connect the marked stone at A or make the ko bigger by cutting at B. On the other hand, he may also answer White's move. If White believes the situation around the ko is important, he should play a move that needs to be answered. Such a move might be white 14, which needs a response at C or D.

Diagram 4: Let's see what happens in each case. First, let's assume Black just connects at 15 in response to White's marked move. White could then play at 16, which would split Black's marked stones and lay waste to Black's top corner. This is bad for Black.

Diagram 5: Another alternative is cutting with 15. However, after white 16, it appears that, no matter where Black plays his next move, White will connect where he has taken the marked black stone. Black 15 seems unreasonable.

Diagram 6: What happens if Black decides to answer the white marked stone with 15? White can now recapture with 16. However, if Black captures with 17, White faces a difficult choice again. Should he connect at A, followed by black B? Or should he block at B, followed by Black recapturing at A? Regardless, White cannot capture the entire upper left corner. This looks grim for White. The same is true if Black plays at 17 (alternative D in Diagram 3) instead of 15.

Conclusion: As you can see, a ko can be a very tricky situation. First, if you want to win a ko, you must play a move called a ko threat. Second, if you win the ko and ignore the ko threat (Diagram 4), that can be bad. Third, if you play a ko without ko threats (Diagram 5), you may lose big time. Fourth, making a ko threat that loses points (Diagram 6) also is no good.

Solution to last week's problem

Solution: In the situations A through C, Black can capture a few white stones. In situation A, it takes two black moves (1 and 3) to capture four stones (white 2 is not shown). In situation B, Black must first connect at 1 before he can play at 3. Even if White plays at 2 and 4, Black captures five white stones with 1, 3 and 5. Therefore, he needs three moves. Situation C is not so simple. Black must first capture with 1, before proceeding with 3 and 5. In total, he captures five stones with three moves.

Van Zeijst is a four-time European go champion and European representative at the Fujitsu World Championship.