Last week, the results from the first and second rounds of the Fujitsu World Go Championship came in. At the outset of the tournament, most people believed the South Koreans would be on top again, as they have been for the past few years. The Chinese have also recently become stronger.
It came as a big surprise that four Japanese and four Koreans were still standing after two rounds. To make things even more exciting, the Japanese were matched against the Koreans. Among the Koreans is Lee Chang Ho, who was regarded as the strongest player in the world until last year when 20-year-old compatriot Lee Se Dol won the tournament.
Also in the running are O Rissei, who has just lost his Kisei title, and Norimoto Yoda, the current Meijin. Although South Korea is probably the strongest go playing country right now, Japan should not be counted out yet.
The first step--part 4
Last week, we saw how stones could be neutralized without actually being captured. In addition, I claimed you could read about 50 moves ahead and it's no big deal. To make the examples shown here easy to understand, the number of black and white stones don't always match.
Diagram 1: The two marked white stones have a liberty at A, but even if White plays there he will lose three stones when Black captures them by playing at B. The marked black stones have a problem with liberties, too. Even if Black were to play first, he won't be able to escape and he won't increase his liberties by playing at C or D.
Diagram 2: Sometimes it is less obvious how a stone is captured. The marked white stone is trapped in a so-called ladder. What happens if White tries to escape?
Diagram 3: White 1 is the only way to try to escape with and increase the number of liberties of the marked white stone. However, Black can keep White down to one liberty every time. Near the edge, Black can steer the ladder a little with 12, and after white 15, Black captures the lot.
Solutions to last week's problems
Solution 1A: The question last week was, can Black capture the marked white stone by playing at 1? Notice the white stones at A. One feature of the ladder is the restriction of liberties. However, white 10 connects to A giving White three liberties. Black 11 (or B) is useless. White can play at 12 and capture at C or D next. Now Black is in trouble.
Solution 1B: The second part of the problem was to imagine what happens if the stone at A is black. Black A would become part of the trap and the ladder would be shortened. Even without its presence, when Black plays at 1, the marked white stone is doomed.
Solution 2--step 1: Let's have a look at how the problem came into existence. White 18 starts a sequence that leads to disaster. The moment Black plays at 19, White is in trouble.
Solution 2--step 2: Let's analyze the situation on a smaller board to get a better picture of the problem. Here, black 1 represents black 17 in Step 1 above. White should not play at 2 to try to escape. Because the moment he does, black 3 sets up a double threat. If after white 4 and black 5, White plays a defensive move at 6, black 7 will reduce the liberties of White's three stones to two--at A and B. If White wants to make headway against Black, he has to play at C, D and E. That would take three moves. White would lose a capturing race if he played at C. That is why he played at 22 in Step 1, but...
Solution 2--step 3: After white 22 in Step 1, Black can start a ladder with 23. It runs all the way to the upper-right corner into the black stone that is waiting there. Without that stone, the ladder would have been about 50 moves.
Problems
Problem 1: Black plays first and captures the stone at A.
Problem 2: Black plays first and captures the two stones at B.
Problem 3: Can Black play at 1 and capture the marked white stone?
Next week, you can find the answers to these problems here. Or you can find out tomorrow at Ben's Cafe in Takadanobaba, Tokyo (03-3202-2445 or www.benscafe.com), where the English-speaking go community (Japanese welcome) congregates every Sunday, starting at 11 a.m. You can enjoy free lessons until 1 p.m.
Rob van Zeijst is a four-time European champion and European representative of the Fujitsu World Championship.