Diagram 1: The moves through 8 are standard, although the sequence in Reference 1 is more common. Black 9 is not uncommon in this situation. White 14 in combination with 16 is clever. This is a strategy to restrain potential black center influence, Yoda's favorite style (see Reference 2). It is unclear if the result is due to clever play by Yoda or an oversight by Yamashita. Anyhow, the consensus is White already has scored some points.

Yamashita realized his mistake and as a result of his mental anguish, his judgement was temporarily impaired, leading to another mistake. Some people tend to believe top pros are like computers, but even they are influenced by psychological factors, just like us mere mortals.

Since he is aware he cannot close off the center well, Black plays at 19 instead of 21 to make corner territory. The moves through 28 are a one-way street. According to the pros following the game, Black should have followed Reference 3. However, the result through white 28 was not considered bad for Black. However, here Black made a crucial mistake. He ignored what we have studied for the past few weeks: changing the borderline between two competing moyos (territorial frameworks).

Reference 1: Black 1 is the most common response, leading to the joseki through 5. Next, white 6 is a good move, putting pressure on Black's marked stone while alleviating pressure on White's marked stone. Often, Black plays at A to attack White's marked stone and build influence toward the upper right as happens in the real game. However, since white 6 is present, this is not very good for Black.

Reference 2: After black 4, White usually cuts at 5. Black then extends to 6 and white 7 captures black 4 in a clean way. However, even if black 4 cannot escape, it can threaten to do so with B or C. Besides that, Black can cut off White's way to the center with D or E.

Reference 3: Black should have connected at 1. The moves through 12 will likely follow. During the game, Yamashita probably thought this was bad as white 6 and 16 (in Diagram 1) stand out as good moves that countered Black's influence. However, black 13 is a good move. This allows Black to set up a huge framework.

Problem 1: Look at Diagram 1. First, determine where Black's and White's moyos are. Where should Black play after white 28?

Problem 2: Let's not forget go is a tactical game as well. Where should Black play to survive?

The solutions will be carried next week.

Solutions to last week's problems

Solution 1: Black 1 expands his territory while reducing White's. This shifts the borderline. Black's marked stone was swallowed up but White had to play many moves to do so. In the meanwhile, Black expanded his positions on the left and on the right. In the end, White invaded successfully on the left side while Black killed White's group on the lower side to win the game.

Solution 2: Black played sente moves with 1 and 3 to expand his moyo. Before answering black 3 with 8, White played some forcing moves with 4 and 6. Black 9 is a nice move that does not overstretch his moyo while making it difficult for White to come in. Later, White invaded and a battle royal erupted.

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.