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Ponnuki

 

APonnuki Is Worth Thirty Points
    Keywords: Proverb, Shape

[Diagram]
Diag.: ponnuki

The proverb 'A Ponnuki is worth thirty points' tells that the ponnuki shape in this diagram is often very valuable. Especially when played in the center, or some other open space, a ponnuki can exert influence in all directions. The number 30 here is of course just a manner of speaking - what is important is that it is large. One needs a very good reason to allow one's opponent to get one.


[Diagram]
Diag.: tortoise shell

Even better than the ponnuki is the tortoise shell in this diagram, where two stones have been captured. In analogy with the ponnuki proverb, some say that this shape is worth 60 points. Again, one should not take this number too literal, but whatever the value of this position is, it is huge.

-- Andre Engels



The value of a ponnuki depends on wether it appears in the fuseki, the middle game, or the EndGame. Usually the later the game, the less valuable the ponnuki is. The reason for this is, that a ponnuki is thick, which means it is hard (or impossible) to attack a ponnuki. This is because ponnukis can easily be turned into living groups, as they have a rich potential for creating eyes.

A thick shape has strong influence and thus a ponnuki can later be used for attack, for building territory, or as safety haven for retreating invasion stones. By now you should see why ponnukis are worth 30 points.

--ArnoHollosi


BillSpight: I suspect that the 30 points in the proverb comes from the old estimate that a stone is worth 10 points. True, there are 4 stones in a ponnuki, but presumably the shape was formed by capturing one stone, which makes the net number of stones 3. If no mistake has been made by the ponnukier early in the game, 30 points may be an underestimate.

You don't just see ponnuki floating around. E. g.,

[Diagram]
Diag.: Ponnuki not so lucky

Black is obviously overconcentrated.



What the proverb does is warn against this kind of thing.

[Diagram]
Diag.: Not worth it

Black has connected, but at the cost of allowing a ponnuki. The ponnuki is stronger than it looks.


[Diagram]
Diag.: Tewari

If we regard the 3 pairings as roughly equal (although slightly favorable for Black), the ponnuki stone (square marking) is almost a free move.



Kungfu: A comment on what Bill said above: You are right, but the truth is that ponnuni is worth 30 points, but white's framework is worth more especially since it's white's move. Yet I don't know if I would say the game wasn't even.

[Diagram]
Diag.: 19x19 diagram

Something like this, or a variation, is given in a book by Otake Hideo as being an even situation. It's black's move now. It is given in his book "Opening Theory made Easy" under the section title "A ponnuki is worth 30 points". I have played and won about 40% of my games when using this "fuseki", against players of even strength. I actually reccomend it for black to try this at least once, to help point out some faults in black's whole board thinking against players of even strength.
DaveSigaty: Note that ponnuki is not a shape in Japanese. It is the act of capturing an enemy stone with four of your own ("pon" is the sound made by the final stone that removes - "nuki" - the enemy stone -- according to the Go glossary at the back of Yamabe's Gendai Joseki Jiten). As Bill mentioned above, the captured stone reduces the net stone count to only three. Similarly the tortoise shell shape is formed by only four stones net as long as two W stones are captured.

Compare the following two continuations. If the second is equal then the first must be significantly to B's advantage.

[Diagram]
Diag.: A Center Ponnuki


[Diagram]
Diag.: A Center Nuki-less Pon


Kungfu comments: Thanks, Dave. Very interesting point. However I view the result as not too much different, since in 1 above, white has sente, while in 2, black has sente.

Did white give up a stone for sente, and if so, is it worth the difference in board position in such a game?

Kungfu, consider carefully what you are saying. Look at the last diagram above after B plays 7. Is it true that you see not too much difference between:
  • W playing at 8 with B to play next (= the situation in the diagram), and
  • W passing, B playing at 8 with W to play next (= the situation in the previous diagram)?
In other words, you view the situation as not too much different whether you play or pass for your turn? :-) Dave


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