Tactics involve precise reading, good knowledge of shapes, an understanding of vital points and exact calculations of the number of points a move is worth. Visualization is the vital ingredient here.

Certain differences in visualization and its interpretation have led to differences in rules. For example, Japanese rules declare some groups dead while the Chinese rules refrain from judgment and make the players continue to the end.

Diagram 1: Let's start with a situation that demands visualization. The ladder is a basic tactic to capture one or more stones. For example, Black can capture the marked white stone by playing at 1. If White tries to escape with 2, black 3 and others will follow, leading to a ladder type of shape. In the end, Black can capture all of White's stones.

Diagram 2: Often ladders involve stones that either help the ladder or interfere with it. For example, can Black capture white 2 by playing at 7? Do the marked black and white stones interfere or help? How does the ladder evolve?

Diagram 3: Of course, playing out the entire sequence is one possibility. A player can probably visualize the result around move 36 or 38--White will run into the marked black stone while the marked white stone does not interfere. Black 43 takes away the last liberty and White's stones are captured. The stronger you get, the fewer stones you need to visualize the end result. The opposite is also often true--the better you can visualize the stones that are not yet on the board, the stronger you are. So you can make yourself stronger immediately by solving problems that involve visualization.

Diagram 4: In the case of ladders, there is a neat trick to help you visualize what happens. If the marked black stone was on the star point in the lower right corner and the marked white stone was right next to it, the result of the ladder would be exactly the same as shown here, with the stone at the star point in the center with the white stone next to it. And it is exactly the same as if the marked black stone were at A and the marked white stone at B.

Diagram 5: Last week we looked at this situation. We found black 1 keeps his stones alive. As is often the case with corner groups, the 1-2 point is the vital point. If White takes the other 1-2 point by playing at 2, black 3 makes the second eye. White 4 is simply blocked by black 5. Black has two eyes.

Diagram 6: If White plays at 2 after black 1, Black takes the other 2-1 point as well with 3. White can play at 4, but eventually the result will look like this after white 8. (This could be played in a different order or Black or White could place a stone on the cross). Anyway, A and B will constitute two eyes, so Black is alive.

Diagram 7: Do not make the mistake of playing at 1 in an effort to enlarge your territory. White 2 would kill the black group. Even if Black plays at 5, he is doomed.

Diagram 8: Black cannot capture the two white stones inside his territory and live. If he plays at 1, White connects at 2. Black can capture three stones with 3, but...

Diagram 9: White 4 will reduce the black group to only one eye. Therefore, all of Black's stones are lost.

Diagram 10: Now that we have established that Black should not to try to escape his destiny, let's go back to Diagram 7. Black cannot escape so he should not play in this area. In the end, White gets to play at 1, 3, 5 and 7. White can now play at 9 to try to kill the black group. Of course, black 10 will capture four stones.

Diagram 11: Next, white 11 is a good move. Black can only try to survive by playing at 12 to start a ko. White 13 captures the ko first and the reasoning goes that since White can start the ko at any time (after eliminating all of Black's ko threats), Black has no ko threat and has to play 14 at a meaningless point (not shown). White then captures the black group with 15.

Following this line of logic, the Japanese rules would declare the black formation in Diagram 7 dead, while other rules demand that White prove he can actually kill the black stones.

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.