Diagram 1 (1-27): The situation at hand after black 27, is more complex than last week's problem, because there are four moyos (territorial frameworks) involved. Black claims the left and right sides, while White puts a claim on the upper and lower edges.

It is White's turn. How can he restrain Black's potential while building his own moyo?

Diagram 2 (28-33): White 28 is the correct move. The marked stones in the lower right are alive and strong so White should not attack at A. It is better to make Black add moves to his strong stones, such as exchanging white B for black C. That virtually bars White from the right side. Using 28 to make Black take the unimportant side is correct. Black has to follow through to 33.

White still has the initiative. Where should he play next?

Diagram 3 (34-42): White 34 shifts the border between Black's left-side moyo and White's moyo at the top in White's favor. Imagine a black stone at this spot (see Reference 1). White then keeps building his moyo to 40. Black 41 is a good move. It forces White to add a move in his own territory and will slow the development of White's moyo.

Reference 1: White 1 is a tempting move to establish a presence inside Black's sphere of influence. However, after black 4, White has a few problems. First, his stones on the left are still weak. Second, the marked black stone may escape, which is a severe problem because of the presence of black 4. Third, Black may invade at A. White B is answered by black C as he does not need to defend with a move around D.

Problem 1: Look at Diagram 3 and try to guess where Black should play. Again, look at the various frameworks and see if you can shift the border. Also, do a rough count of the territories that can be expected to form.

Problem 2: This is a situation in a game between two top players. White just played the marked stone. How should Black play and implement a moyo strategy?

The solution will be carried next week.

Solution to last week's problem

Solution 1: Yoda (black) played 71 to sacrifice his center stones. White 72 captured four stones in the center, but on a small scale. Black 73 forced 74, making the sacrifice even smaller. In the sequence from 81 through 93, you can see how small Black's center sacrifice was. White invested plenty of stones in their capture, but the territory gained was not so large. Due to this sacrifice, Black won the game by a comfortable 7.5 points.

Reference 2: Black 1 invites white 2. Once White answers, the moves through 10 are almost inevitable. Black 11 connects the marked stones. At the very least, White will have a lot of trouble capturing them. For White their capture is important, while they are expendable for Black.

Want to find out more? Come to Ben's Cafe in Takadanobaba (03-3202-2445 or www.benscafe.com), where the English-speaking go community congregates every Sunday starting at 11 a.m. You can enjoy free lessons until 1 p.m.

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