When formulating a winning strategy, ...
By Rob Van Zeijst
When formulating a winning strategy, many players believe they cannot go wrong as long as they continue attacking their opponent. However, this often leads to overextending oneself, creating weaknesses. While the opponent is weak, which is generally the case as long as the attack lasts, there is no problem. The problem arises when the attack ends or when the opponent becomes stronger. That is when the opponent will lash out and the position could be reversed.
Ideally, stones should reinforce each other to cover weaknesses. Such a formation is said to have good shape and the stones will work together efficiently. In go, good shape and efficiency are regarded as synonyms. In other words, if a pro says a formation has a good shape, he means that the stones are placed efficiently and work well together. In general, Japanese professionals rely on a good shape, while South Korean pros will play anything that works.
Tsuke-koshi
Diagram 1: The white stones make up a keima, or knight's jump. Although this formation is often used to attack, it has a weakness--it can be cut, especially if there are many hostile stones in the neighborhood. If Black has the marked stone in place, he can cut with the 1-3 combination. Usually the prerequisite for this cut is that the ladder white A, black B, white C, black D, white E, etc. is good for Black. In other words, if his cutting stone has an escape route, Black can cut with 1.
Diagram 2: To demonstrate the keima in a real game, let's have a look at the JAL Women's JAL Haya-go (Lightning Go) Championship between Yoko Inori and Narumi Osawa (white) that was broadcast early Sunday morning on TV Tokyo. These are the first 40 moves. The moves through 28 are unremarkable, but then Black plays a keima at 29. This leaves behind a cut (at 40), but this time, the ladder is bad for White. Instead of 29, Black could have played at A, which might be followed by white B, black D, white E and black F. This would be a good result for Black. However, White may not answer at B. He probably would extend to G. Black no doubt thought 29 would apply pressure on White, and his opponent would answer at C, followed by black D, white E and black F. However, White strikes at 30, an extremely aggressive move that is aimed at cutting at 40. Black refuses to defend against this move. Instead she forces White into a low position with 31 through 34, then cuts off White's escape route with 35. White reinforces with 36 through 39, then cuts with 40. This is the tsume-koshi cutting technique. Let's see how Black responded.
Diagram 3: Since the ladder is bad for Black, she defended with 43 and 45. White then started an attack in the center. However, after black 61 and 63 the attack fizzles out and White lands up in a bad position. However, White comes up with a great move at 80. Black 81 through 85 are bad moves as White was able to cut off eight stones with 86 through 92. This combination won Osawa the game and the tournament.
Solutions to last week's problems
Solution 1A: The question was what should Black do in this situation (using a tsuke-koshi). In a game between Satoshi Kataoka (black) and Shuzo Awaji, Kataoka, whose three stones are under pressure, played the combination 1 through 7. White did not defend the corner right away, so Black exchanged 9 for 10, which was necessary to stay alive, and played 11 to escape.
Solution 1B: Norimoto Yoda (black) and Koichi Kobayashi had a similar situation in a different corner. Due to the presence of the marked black stone, after 9, White made the sente exchange 10 through 15, then switched elsewhere. Later, Black started a ko with the sequence black A, white B, black C, white D, black E and white F. Black won the ko but lost the game.
Solution 2: The white marked move is an overplay. Black's tsuke-koshi tesuji of 1 and 3 and the cut of 5 isolated the marked stone. White had no choice but to go along with 2, 4 and 6. Black can now play at A or B to bottle up White's marked stone.
Problem 1: White is in trouble. Just connecting with 1 leads to the sequence through 6, and White may well be doomed. Instead of 1, where should he play?
Problem 2: Black 1 and 3 cut off the marked white stone. However, after white 10, Black's marked stone is cut off and his position is not great. What sequence would have been better for Black?
Hint: Use the tsuke-koshi tesuji but do not play 1 right away.