Some 9-dans are better than ...
By Rob Van Zeijst
Some 9-dans are better than others. That might be obvious, but many people wonder what a pro would play in a particular situation. Pros are quite creative in finding solutions to a situation and, unless there is an obvious one, they start narrowing down their search until there are only a couple of possible candidates. Taiwan's O Rissei, 9-dan at the Nihon Kiin and a former Kisei, is among the best problem solvers. He often comes up with such unconventional moves that others just shake their heads in disbelief. To become a top problem solver, you must be aware of conventional wisdom, but not necessarily stick to fixed ideas. O says the best way to come up with the moves you need is to practice tsume-go (life-and-death) problems every day.
Let us have a look at a recent game between O (White) and Satoshi Yuki, the top player in the Kansai area, to decide the challenger for the 31st Kisei title.
Diagram 1 (1-38): White starts hostilities by cutting with 12, which leads to a series of tsume-go problems. Usually Black would follow Reference 1. Black 13 in the actual game is the strongest response. With 20, White aims to try to kill Black's corner with A (see References 3 and 4). So Black responds with 23. White must answer with 24 and 26. White 28 is a clever move. See Reference 2 for the reason why Black replies with 29. White 36 seems to be a strange move. White really wants to connect at 37, but black A would make his corner group alive and connect with black 29, splitting White into two weak groups. After 38, White wants to play at B to kill the corner group. Lets see what happens.
Reference 1: After black 1, the moves through 12 are a set pattern. Black 7 and 9 may look like odd moves but they ensure Black can later play at D in sente after first exchanging A for B and blocking at C.
Reference 2: In response to White's marked stone, if Black cuts with 1, White would play at 2 and sacrifice two stones in the sequence through 7, and then extend to 8. Note the exchange of the marked white stone for black 1 is a gain for White.
Reference 3: White 1 is the move to try to kill the corner. But Black 2 and 4 are a strong attack. White can somehow live with 5 through 11 but Black can now launch an assault with 12 and 14. Even if White does survive this, Black will build a huge center wall.
Reference 4: However, Black can also try to stay live with 12. If White goes ahead and plays at 13, 15 and 17, black 18 through 26 put him on the spot.
Diagram 2 (39-75): After black connects with 39, White exchanges 40 for 41 before moving to the center with 42 and 44. Black must now defend at 45 to safeguard his corner group. White 46 is the vital point to build up the center. White grabs the initiative with 46 through 52. The exchange 53 through 56 strengthens Blacks center in preparation for the cut at 57 and 59. White seems to be in trouble now. However, after white 68 and 70, it seems Black is under more pressure than White. Note that a white move at A is not particularly dangerous because Black would cut with B, followed by white C, black D, white E and black F, which kills the marked stones faster than White can destroy the center.
Solutions to last week's problem
Solution 1A: White 1 kills Black's group. Black 2 prevents White from connecting underneath. However, white 3 is the vital point. To make two eyes, black 4 is the most obvious move. But after white 7, Black must connect at A, and that kills his second eye. In other words, Black is dead.
Solution 1B: After 3, Black can try 4. However, white 5 and 7 kill the black group. White 7 is necessary or Black will play there. If there is a black stone at 7, White can't kill Black by occupying all of Black's outside liberties first and then playing at A or B. If he does, Black will capture those four stones, which gives him a space wide enough for two eyes.
Solution 2A: White 1 is the best move. Even if Black captures one stone at A, White captures three stones. Confused? See Solution 2B.
Solution 2B: This is the situation after Black captures White's stone. White can capture three stones by playing at A. This situation is called a snapback.
New Problems:
Problem 1: It is White's move. Where should he play?
Problem 2: White is trying to kill Black's group. Black 2 presents a new problem. How should White proceed?
Van Zeijst is a four-time European go champion and European representative at the Fujitsu World Championship.