Lesson 142: Mastering Carpenter’s Square (5)
In the previous lesson, you've seen two variations of the Carpenter's Square, one with an empty intersection and the other with a bend. There can be other ways to go further with more variations, but mine are a different example with an empty intersection, and another one with two bends. I hope they help you become less dizzy.
The position in this diagram is different in two ways from the basic Carpenter's Square; there is no black stone at A to make Black's shape perfect, and White's siege has an empty intersection also at A. To tell the conclusion first, these two points kill the black group. Of course, the fatal attacking point here is White 1.
I expect now you will try Black 2 as the first possible move. However, because Black has a stone at 10, the attempt to make a dual-life as before cannot succeed.
It is obvious that Black 2 is not any better as White can play 9 after the exchange of White 7 and Black 8. Therefore, if Black's shape is flawed with A, it cannot be saved even with a ko.
However, a presence of a bend like the △-marked black stone can change the whole situation. Now it is possible for Black to make a ko.
Do you remember that when there is a bend, Black 2 here is a better move than the attachment at 4? That is also valid in this position. You just be careful not to turn with 3 instead of Black 2.
For the next variation, let's look at the position with two bends at the △-marked points. White 1 is a normal attack, but the fiercest as you know. Okay, then, what help do these two bends provide to the black group's life? For sure, Black can make a direct ko by playing at A and following the sequence already shown in Diag.5. However, that's out of the question.
In this case, Black's attachment becomes a good move again. You may remember that White 3 is one of the ko-making moves when Black attaches at 2. However, with the △-marked black bend, the situation is totally different. As you see, Black can play 6 owing to the bend and the group is perfectly safe. By the way, you remember that White's answer with 6 instead of 3 against Black's attachment at 2 just let Black live with a dual-life, don't you?
What about White 3 here? This can be either good or bad depending on the follow-up. However, White 5 is not a good move because Black can make a dual-life with 6 to 8 owing to the Black's bend at △.
When Black connects at 4, White 5 is a good move. Of course, White still cannot kill the black group right away. The result of the sequence up to 8 is a thousand-year ko.
The writer is a baduk professor at Myongji University and a professional player of the game.