Diagram 1 (moves 29-50): It is hard to imagine why Yamashita played 29 and 31 to capture two useless stones (the marked ones), and then played a wishy-washy move at 33. Locally, this is a vital point to shift the border between the black and white moyos. However, white 34 ruins all of Black's efforts. Black cannot deal with this intruder. His reply at 35, 37 and 39 gives White no trouble--he just moves out to the center. Black 41 is an important move--imagine a white stone there--but in itself, it does not make or destroy any territory and has no attacking potential other than forcing White to capture with 42 and 44, moves he is happy to make anyway. He could free his marked stones with his next move if he wanted to. Black 45 is a good move for connecting, but White forces with 46 and 48, then sets out to develop virgin territory with 50.

In the end Black had to resign.
So what went wrong? See solutions to last week's problems below for the answer. Before doing so, however, first look at the next few diagrams for an important hint.

Diagram 2:The moves through 11 form a joseki (common corner exchange). However, this does not conclude the joseki. Where should White play next?

Diagram 3:White should force with 12. After Black's answer at 13, White can play at A to try to capture the marked stone. Conversely, if Black is strong in this vicinity, White is sometimes better off playing at B to make a strong base. Later on, depending how the game develops, C may become a vital point for both sides to shift the border between the spheres of influence.

Diagram 4:The moves through 12 constitute part of a joseki. As you can see, both parties are trying to establish centers of influence. Where should Black play next?

Diagram 5:Black 1 is the correct move. White will then play hane at 2 allowing Black to capture the marked white stone with 3. White can now extend to 4. Aiming at the squeeze of white A, black B and white C, black connects where he captured the marked white stone. There is still a cutting point at D, though. Instead of 4, White could also play at E to defend against the cut at D.

Reference 1:Black 1 is no good. It captures the marked stone, but with 2 and 4, White gets tremendous thickness in the center thereby pushing back Black's potential territory while expanding his own.

Reference 2:After black 1, what happens if White saves his marked stone by extending with 2? Is this bad for Black? Not really. First, Black extends to 3, forcing White to play at 4. Black's center position is very strong now. Next, he may want to play at A, but the move is a little passive. A move at B is very powerful, though, and if White defends at the top, Black can reinforce his corner position with C, followed by white D and black E.

Solutions to last week's problems

Solution 1:If we retrace the moves for this solution, Black has a tremendous opportunity to shift the border between his moyo and White's. Black 1 is the vital point. After White captures at 2, Black presses him with 3. White 4 is crucial, but his position is low and shows little promise for expansion. Black, on the other hand, can play at 5 to develop a huge territory on the upper side of the board. This looks more like Yamashita's style; he was not his usual self after White threw him off earlier in the game.

Solution 2:Black 1 (or A) is correct to make two eyes. This makes A and B miai. For example, if White plays at A, black plays B and vice versa.

Reference 3:Black 1 makes more space, but white 2 and 4 kill the black group.
We will discuss this group in detail next week.

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.