Table of contents | Table of diagrams Diamond shape Goodness of Diamond shape Invest 4 stones to form a diamonad shape Diamond shape Ponnuki |
This shape is called a diamond or diamond shape.
One should avoid the opponent forming this shape because it exerts good influence from all sides.
It lays a potential eye.
It is difficult to capture this shape too. When one plays at any point at "a". The opponent can extend to "b" and threaten to capture stone at "a" by a ladder.
It can later convert to some other powerful shapes (eg: honeycomb)
However it is not a good idea to invest 4 stones to form it artifically. Consider the following:
Bill: I believe that this is the diamond shape. (See T. Wolf, The diamond. British Go J. 108 (1997) 34-36.)
aLegendWai: Hehe... An interesting diamond. I would like to call it compressed diamond. However it is no longer a good shape than the normal one.
A compressed diamond cannot be in good quality. ^^
In contrast, a ponnuki is the process of capturing a single stone leaving such a shape, not the shape itself. [1]
Charles Matthews: Ponnuki implies local tally BBB (four black stones played, one white captured, 4 - 1 = 3). If you make a diamond as Black without capturing a white stone that is local tally BBBB. The former is proverbially worth 30 points, i.e. ten points when you divide by the tally; the latter would therefore give only 7.25 points per play.
[1]
aLegendWai: It is just my idea though.
To me, this term is somewhat superfluous. It seems we don't need to go down to this details and classify between a diamond shape and the process of a diamond shape formed by capturing a stone (ponnuki). The formation of a diamond shape will not change its properties/goodness.
Eg, When we form a Tortoise Shell ourselves, it is called Tortoise Shell.
When we form a Tortoise Shell by capturing 2 stones, there's no special name for the process. And it is also called Tortoise Shell.
Although it is surely better for us to form Tortoise Shell by capturing because you form it naturally (without investing extra stones on you own. But it is not necessary for us to make 2 terms for them.
By the way, is it only a diamond shape has such kind of a classification?