Two-stone edge squeeze

    Keywords: Tesuji, Tactics, Go term

Chinese 1: 大头鬼 (d tu guǐ, big-headed ghost)
Chinese 2: 秤砣 (chng tu, steelyard weight)
Chinese 3: 拔钉子 (b dīng zi, pulling nails)
Japanese: 石塔シボリ (sekito shibori)
Korean: 귀삼수

Two-stone edge squeeze

The two-stone edge squeeze tesuji , also known as the "stone tower", is commonly used in capturing races and can occur not just in the corner, but also anywhere on the edge. Also known as stone monument tesuji, stone tower tesuji, or stone pagoda squeeze.

See also two-stone corner squeeze.

Table of contents Table of diagrams
White to play
Solution
Solution
Solution
Blacks best defence
[Atari] at the wrong side
Two-stone edge squeeze (Black to play)
Two-stone edge squeeze (part 1)
Two-stone edge squeeze (part 2)
Variation
Black loses the capturing race


Example 1

[Diagram]
White to play  

White to save his group.


[Diagram]
Solution  

W1 and W3 form the first part of the two-stone edge squeeze tesuji. Note that B2 is forced, as atari from the other direction leads to the capture of one of the two groups cut apart.(see later) W1 also prevents the atari at a.


[Diagram]
Solution  

The throw-in at W1, which is the second part of this tesuji, forces the capture at B2. W3 is an atari on three Black stones; White lives if these three stones are captured (see capture three to make an eye).


[Diagram]
Solution  

If B1 connects, then after W2, it's one eye to none. White wins the capturing race.


[Diagram]
Blacks best defence  

Blacks best defence after W1 is to save his black+square stones with B4, forcing W5. Later Black can play at a as a big ko threat: White needs to answer at b or his group dies.

Willemien Is it not better to also keep the B4 - W5 exchange as ko threat?

W at 4 would remove the ko threat and capture the black+square stones. That would be bigger than W1.


[Diagram]
Atari at the wrong side  

Giving atari at the wrong side makes it all too easy for White. Not only Black can do nothing to prevent White capturing the black+circle stones, but also White can in the endgame capture the black+square stones (by playing at a). But probably a tenuki elsewhere is bigger than this.



Example 2

[Diagram]
Two-stone edge squeeze (Black to play)  

This particular position is also known as the two-stone corner squeeze.


[Diagram]
Two-stone edge squeeze (part 1)  

In this capturing race, B1 is necessary to reduce White's liberties. The first part of the two-stone edge squeeze tesuji is the descent at B5.


[Diagram]
Two-stone edge squeeze (part 2)  

The next part of this tesuji is the throw-in at B1. In this position B3 is yet another good move, if W4 prevents the atari, B5 wins the capturing race.


[Diagram]
Variation  

Depending on the condition on the left side, one might argue that W4 is a better move. But it does not change the fact that B5 and B7 capture the key stones.


[Diagram]
Black loses the capturing race  

B1 is too slack. Up to W4, White wins the capturing race by one move.


pwaldron?: John Power remarked to me recently that the actual translation for this should be tombstone squeeze rather than a stone tower or (from the [Slate & Shell] translators) stone pagoda squeeze. This discovery was apparently made after a fair bit of digging around in some dictionaries. I have no Japanese knowledge of my own and take this on faith, but looking at the position the two stones being squeezed do rather resemble a tombstone.

Bill: I like tombstone squeeze. :-) But it is not a literal translation. Tombstone in Japanese is 墓石 . However, it appears that the pagoda derives from the word stupa, which began as a burial mound for the Buddha's remains. And a tombstone can be a stone pagoda.

John F. I wrote about this tesuji in the new Go Companion as being the case of having perhaps terms than any other (some not mentioned here). Although I didn't say so there, the reason sekito is hard to find in ordianry Japanese dictionaries is that it was a term invented by Maeda Nobuaki (1950s, I thnk), and he intended it to mean the shape of a Japanese gravestone. Although I used tombstone in GC, it was with reservations. I tend to associate a tomb with a large underground burial space, whereas a Japanese gravestone really marks a place for burial of a tiny urn (if that), but on looking it up I found that tomb can apparently be used for a burial spot in general, so I stick with that. In any event, I think any references to pagodas and stupas are de trop.

BuggyMind: (consults a dictionary) I think the phrase 'de trop' is de trop.


Two-stone edge squeeze last edited by 60.240.145.232 on December 5, 2012 - 02:59
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