Sustainable development is a term ...

By Rob Van Zeijst

Sustainable development is a term that usually refers to the economic, political or cultural development of a country or region and entails "comfortable efficiency." This signifies an absence of overextension or misapplication of resources. However, it also implies that a lack of development or insufficient development leads to problems. But most of these problems do not become apparent immediately. Overextension and misapplication of resources often show short-term benefits, leaving behind weaknesses. When exposed, these weaknesses may cancel out any progress made earlier. At the same time, avoiding risks leads to underdevelopment. This is true of go--there are plenty of places to develop without trying to conquer the entire board.

Extensions

As mentioned last week, the rule of thumb for developing a lone stone on the third line is a two-space extension, while the extension would be greater for a stronger formation.

Diagram 1: Now let's have a look at the beginning of a game between Kimio Yamada (black) and Norimoto Yoda that they played in the Honinbo league a few years ago. The issue of what extension to make comes up when White plays 6. He could also have played at A. What is the difference between these two moves?

Diagram 2: Suppose White plays at 1. This allows Black to play at 2, the optimal extension from his marked stones. There is a weakness at A, but a white invasion here is usually more dangerous for White than Black. In addition, black 2 exposes white 1 as an overextension, forcing White to defend at 3. B is the traditional way of defending 1 while strengthening the corner. A modern way of thinking is playing at C. This leaves the right open to an invasion, but quickly develops the lower side. In short, white 1 is not bad, but for today's go it lacks spirit.

Diagram 3: If White plays at 1 as in the game, Black would be reluctant to play at 2 because this extension is narrow in relation to the strength of Black's marked shimari (corner enclosure). However, White's extension from his marked stone to 1 is also wider and therefore weaker. This position needs reinforcement around 3. Even if Black invades at A, white B, black C, white D, black E and white F might follow, with White gaining the initiative. At this point, White does not need to worry about this invasion.

Diagram 4: Since extending from his top right would be a bit cramped, Black wants to develop the wider lower side. Black 7 is one way to do that. White's simplest response is A. However, since White wants to use his marked stone on the left, he plays a hasami (pincer) move at 8. Black chooses to invade at 9 and the sequence through 15 follows. As a result, Black gets territory while White builds influence. It now becomes important who will play on the right first. Black could cut at B or invade around C, while White wants to extend to D. If Black extends to E, white F is a good response, reinforcing against a black invasion while building up White's framework. However, white 16 is more important now. The reason Black pincers at 17 is to prevent White from making an effective extension to G.

Solution to last week's problems

Solution 1: White 1 is the usual move in this situation. Black can now pincer from A or from 2. No matter which move Black chooses, White can always make an extension to A or B. However, if Black chooses 2--the most common choice--White will usually extend to 3. After black 4, White generally plays elsewhere. Note that if White plays immediately at 3, Black will play a hasami around 1, which is also an ideal extension from Black's top right. This is bad for White.

Solution 2: White rarely allows this situation because Black's extension to 1 is very good. If White extends to 2, Black jumps to 3 to make a box-shaped formation. White should play at A, but then it becomes obvious Black's two stones at 1 and 3 make more territory than white 2 and A. If White does not play at A, Black can invade at B or increase his influence in the center with A, forcing White to play at B.

Problems

Problem 1: Sometimes Black invades at 1 to attack White's marked stone. How does White cope with this move?

Problem 2: This situation is very common. Where can White invade on the right? Find a few suitable moves and look at the advantages and disadvantages.

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