21. Invading a Moyo
Attach to Settle Your Stones

by Richard Bozulich

In Instalment #10, we saw an example of the side attachment against the one-space enclosure that was used to invade a large-scale moyo (sphere of influence). In this instalment, the side attachment is used to invade a much tighter moyo. As a result, the invader comes under a severe attack and has to quickly find a way to settle his stones.

Highlight Diagram
Highlight Diagram
This position arose in a quarterfinal game of the 32nd Ryusei tournament between Cho U 9-dan (black) and Takeshita Ryoya 2-dan. It was played on October 12, 2023.

Cho U was one of the top players in the early 2000s. He won the Kisei title three times, and the Meijin title five times. His opponent in this game was only 18 years old. The fact that he was able to win his way into the quarterfinals of this tournament indicates that he may be a top contender in the future.

White has just attached with the marked stone. This move is the same as the one that was played in the game featured in Instalment 10 of Go World Online. However, in that game, White had nearly a whole side to establish a base for his stones. In the game presented here, White has much less room to maneuver.

Figure 1 (1–42)
Figure 1 (1–42). A good strategy
These are the moves that led up to the position in the highlight diagram. With his wall in the top right and his position in the lower right part of the board, Black has staked out an enormous sphere of influence. White has to find a way to establish a position somewhere within this sphere.

Since White's position on the upper left side neutralizes Black's thick wall to the right and Black's territory on the right side is open at 'a', invading with the attachment at 42 seems like a good strategy.

Figure 2 (43–50)
Figure 2 (43–50)
When White turned at 46, Black attacked with 47. White 48 is the key point; Black must answer with 49 and White makes shape with 50.

Ishida Yoshio, who was the commentator for this game, was not too enthusiastic about this move. He noted that Black might later play at 'a' or 'b', and White would have fewer ways to make eyes for his group. He suggested the following two diagrams.

Dia. 1
Dia. 1. Attach to settle your stones.
White could attach at 1, then clamp with 3. This follows the proverb 'attach to settle your stones.' If Black connects at 4, White can atari with 5, then jump to 7.

Instead of Black 4 —

Dia. 2
Dia. 2. Variation
Black might atari with 4. After the moves to Black 8, White settles his stones with 9 and 11. This diagram and Dia. 1 give White a more resilient shape than the one he got by playing 50 in the game.

Figure 3 (51–64)
Figure 3 (51–64)
Black attaches with 51 and White hanes with 54. After the exchange of 60 for Black 61, White forces with 62, then jumps to 64.

Dia. 3
Dia. 3. Making eyes at the bottom.
Instead of jumping to 64 in Figure 3, it would be better for White to make eyes at the bottom by attaching at 1. After White 5, Black must extend to 6 (White threatens to atari at 'a'), so White can make an eye at the bottom with 7.

What about Black 59 in Figure 3? Couldn't Black atari at 60 instead?

Dia. 4
Dia. 4
If Black ataries at 1, White ataries with 2, then ataries two stones with 4. Black connects at 5.

Next —

Dia. 5
Black 13 connects at the marked stone
Dia. 5. White's success
White ataries with 6 and the sequence continues to 14. White ends up with good shape, nullifying the influence of Black's thick wall in the upper right. This is a good result for White, so cutting with Black 1 in Dia. 4 seems unreasonable.

Figure 4 (65–100)
Figure 4 (65–100). Only one eye
Black 85, in combination with 69, was a big move. White now has to worry about making eyes for his group on the right. After White 92, the situation is not urgent, as White still has plenty of room to maneuver above, but the eye space White has constructed below 92 can make only one eye. This is bad aji that White will have to contend with later in the game. For example —

Dia. 6
Dia. 6. Only one eye
Black might exchange 1 for 2, then make a placement at 3, and White's eye space can make only one eye. At this stage of the game, these moves may seem far-fetched, but White actually had to contend with this bad aji later in the game.

Let's fast-forward to White 146.

Dia. 7
Dia. 7
White has just defended with the marked stone (move 146).

If Black connects at 1, White would like to expand his territory with 2. But Black would then push in with 3 and make a placement with 5. After Black 7, White's group is dead. Therefore, White can't play at 2; he has to defend at 3, so Black can play at 'a', preventing White from expanding his territory on the left.

Figure 5 (147–157)
Figure 5 (147–157). Black is ahead.
In the game, Black played on the key point of 47 and White linked up his groups with 48 and 54. With 57, Black has made a big dent in White's moyo on the left.

Figure 5 (157–220)
Figure 5 (158–220)
220 moves.
Black wins by 7½ points.

The move-by-move game record can be found at Cho versus Takeshita.
Recommended reading
This game provides some good examples of sabaki, especially Dias. 1, 2, and 3, which put to use the proverb 'attach to settle your stones' (see Essential Go Proverbs, pages 447 – 461). For a comprehensive book on the topic of sabaki, see Sabaki — The Art of Settling Stones.