Diamond

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Table of contents Table of diagrams
Diamond shape
Diamond alive in the corner
Diamond dead in the corner
Diamond in the corner
corner
Diamond shape
Ponnuki
Kajiwara Takeo - Fujisawa Hideyuki, 1958-05-21

Diamond Shape

[Diagram]

Diamond shape

This shape is called a diamond or diamond shape.

[Diagram]

Diamond alive in the corner

iopq: A diamond survives in the corner. It's sometimes useful for invasions or ko threats to know this. Don't let one complete in the corner! Circled points are ko threats for white.

[Diagram]

Diamond dead in the corner

This shape is dead, though.

[Diagram]

Diamond in the corner

This is life based on who gets to move. White can play the marked stone as a ko threat.

[Diagram]

corner

White can move in the marked point to kill Black, just knowing about the diamond in the corner! If the diamond does not complete, Black dies.


Bill: I believe that this is the diamond shape. (See T. Wolf, The diamond. British Go J. 108 (1997) 34-36.)

[Diagram]

Diamond shape


Ponnuki

[Diagram]

Ponnuki

In contrast, a ponnuki is the process of capturing a single stone leaving such a shape, not the shape itself. [1]


Difference between Ponnuki and Diamond

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 7.5 points per play.


Forming a diamond


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