How to Play Go (Weiqi) – Lesson 7

Lesson 7: Basic Capturing Techniques

7.1 Atari Techniques

Many times you try to atari a group, but your opponent simply adds another stone to it and avoids capture, right? However, under some circumstances, you can make use of the surrounding stones you have, and atari your opponent’s stones so that they have to run smack into your surrounding stones, and bingo! You have all of them captured in your network of stones.

In Diagram 7-1, black 1 makes use of his four-stone network to capture the white stone. If he ataris at A instead, then white will escape at 1. Now black is aiming to capture the stone at A. However, if white foolishly plays at 2 in Diagram 7-2 in his bid to save the stone, he will be in for an even bigger capture when black plays at 3.

Diagram 7-3 demonstrates another example. Five stones versus two stones – definitely more advantageous to black. So black plays at 1, ready to whack the two white stones off the board at A anytime. Yet the resistance put up by white in Diagram 7-4 is useless. White 2 tries to squeeze out through the narrow passageway, but black 3 blocks it before white succeeds, and makes a clean sweep of three white stones.
 
7.2 Double Atari

As the name implies, double atari occurs when you atari two groups silmultaneously, such that your opponent can’t save both groups at the same time.

Black 1 in both Diagram 7-5 and Diagram 7-6 are examples of double atari, threatening to capture white stones at A and B. But white can only choose one out of the two points, but not both. Hence black will get to play at the other point to capture the other stones.

7.3 Capturing A Stone On The First Line

We take a look at Diagram 7-7, and we see that the black stone is on the first line at the edge of the board. So white 1 ataris, forcing black to the edge. For white to atari at A is a mistake: black will gladly play at 1, making the two white stones scattered. It is no good for black to attempt the escape at 2 in Diagram 7-8, and white pursues with 3. White continue to press the black group to the edge, and finally, the great escape plan of black becomes its great sacrifice plan when the black group runs smack into the corner – and no way out. Actually, you don’t need to play white 9, and do you know why?

7.4 Capturing A Stone On The Second Line

We show a black stone on the second line from the top, next to two white stones in Diagram 7-9. White first to capture the black stone. Answer: atari at white 1. Playing at A instead is a mistake. Black 2 in Diagram 7-10 is futile, as white 3 and 5 keeps black at the edge and black only loses more.
 

7.5 Net

Chasing a thief too closely may just allow him to escape, while waiting for him at the exit might just nab him nicely. The net is also a very common capturing technique, but it just doesn’t atari the target stones.

The simplest of the net is shown in Diagram 7-11. Black 1 doesn’t atari the white stone, but it catches the white stone nicely. White’s struggle to break out of the net in Diagram 7-12 only allows black to have a larger capture. While white 2 and 4 pushes out of the net, black is already waiting to play at 3 and 5 and white has no exit route.

Black 1 in Diagram 7-13 is also a net. The proof is shown in Diagram 7-14 – white simply couldn’t save his two stones. Notice that while white 2, 4 and 6 tries to escape, black 3, 5 and 7 blocks white’s exit. A caution on nets: not all moves that look like nets will capture the opponent’s stones. Some so-called nets are having holes that are simply too big and the fish inside simply swims away through these holes.

7.6 Ladder

This capturing technique is also very basic, but the ladder is slightly more complicated and needs more elaborate explanation. Ladders can be very powerful, sending your opponent’s stones across the whole board and then capturing them at the other end of the board. However, the wrong use of ladders can wreck very heavy damage on your game. Both in the past and present, ladders that went astray have cost entire games, including those in professional tournaments. So use ladders very carefully, but once you have mastered ladders, you will find them very easy to use, and please feel free to use the ladder when the opportunity comes.

Introducing you to the ladder – white 1 in Diagram 7-15. We all see that the area in the upper right corner is all empty – this is for simplicity sake. Diagram 7-16 shows when black tries to save his stone, but white keeps atari him on alternate sides, forcing black to go in a zigzag way, until white 23 captures all the black stones. It is worth noting that ladders imply repeatedly atari the opponent’s stones until they find no way to evade capture.

So we see that the ladder in Diagram 7-15 runs diagonally to the upper right. Diagram 7-17 is a replica of Diagram 7-15, with six diagonal lines added. If there are black stones on any of these six diagonal lines, then the ladder will fail, so white would be in for a disaster if he tries to chase the black stone.

Diagram 7-18 has a black triangle stone added in the path of one of the diagonal line. White 1 onwards tries to capture black, but the ladder doesn’t work. When black connects at 10, white could not continue chasing black and had to face the music. Black will have the pleasure of choosing which double atari (marked as X) on the white stones full of cutting points.

Now suppose there is a black triangle stone in Diagram 7-19, and white embarks on a ladder. The sequence to black 12 shows the result: black 12 now ataris the white stone marked 9 instead, so the ladder fails. The triangle stone in Diagram 7-18 and Diagram 7-19 is known as a ladder block.

If the stones in the pathway of the ladder consist of a mishmash of black and white stones, then please read out the ladder. There is no magic formula for such cases. Examples are Diagram 7-20, Diagram 7-21 and Diagram 7-22. Try finding out whether white playing at A can capture the black stone, and if you shift the triangle stones one line to the left, right, up or down, and you may find that the result changes. By the way, the ladders in Diagram 7-20 and Diagram 7-22 work, whereas the ladder in Diagram 7-21 does not.

If it is possible to use the net and the ladder to capture a group, always choose the net. Diagram 7-23 shows black 1 netting two stones, and if white 2 plays at the corner star point, black can ignore white and play elsewhere.

Diagram 7-24 shows black 1 choosing a ladder. White 2 becomes a ladder block, and black must play at 3 to really capture the two stones. Now white can play at 4. Now we can see that choosing the ladder allows white to play two moves at the corner. This means that using the net is more efficient than the ladder, when both are possible.

7.7 Snapback

The snapback is a sacrificial strategy. Sacrifice one or more stones, and then take the opponent’s stones off the board. Perhaps the snapback is the hardest to see among all these basic capturing techniques in this lesson.

Black 1 in Diagram 7-25 is a snapback. What if white 2 captures black 1 in Diagram 7-26? Black 3 in Diagram 7-27 will remove the three white stones off the board. Note that stones caught in a snapback have only one liberty.

White 1 in Diagram 7-28, Diagram 7-29 and Diagram 7-30 causes a snapback. For Diagram 7-30, if black takes the two white stones, white can play at 1 again. Surprised? Go and surprise those who do not know this!

End of Lesson 7
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Atari At Work

The atari is very, very common in Go, happening many times in almost any game. However, some people are just blind to ataris. The ability to see that whether a group is under atari actually is a sign of your strength in Go. Some beginners can’t see ataris very well, losing the chance to capture opponent’s stones or causing many of his stones to be taken off the board. Failure to see ataris is a very gross error – very often it costs entire games. To get stronger one must learn to see where and when the atari occurs.

Can you see what black 1 is trying to do in Diagram 7-31, Diagram 7-32 and Diagram 7-33? How should white play? In all of the cases, black 1 ataris the white stones – aiming to do a capture at B. White should answer by playing at A. Imagine how many stones are lost when one fails to see the atari? Woe betide those who fails to see ataris, no wonder such people keep losing Go games, and then complain that Go is not the game for them.

Let us end off this topic by using a so-called ladder as an example. In Diagram 7-34, white plays at 1 and both players agree that the ladder works, so black should allow white to play at A to capture the three black stones. They give the sequence in Diagram 7-35 as the proof: until white 15, black is dead. Ridiculous! After black 2, the triangle white stone is under atari, and anywhere in the sequence after black 2, black can remove the triangle stone off the board. Hence, the ladder doesn’t work after all.

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