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Eyes, life and death · Lesson 21

Making and destroying eyes: who takes the vital point?

Whether an inner space can become two eyes depends on its shape and who plays first. Dividing your own space into eyes is eye-making. Taking the opponent’s vital point to prevent that is often called an eye-destroying move.

Black initially encloses three empty points in a line. With the outside sealed and no external rescue in this example, Black E5 first leaves eyes at D5 and F5. If White takes E5 first, Black cannot make two eyes inside.

Straight three, bent three, straight four, bent four, T-shaped four, bulky five and flower five describe the shape of eye space. Equal-sized spaces can have different vital points. Plenty of empty points alone does not prove a group is alive.

Begin with why straight three needs the middle point. More complex eye shapes also depend on outside liberties, surrounding connections and ko. Do not apply one local diagram’s conclusion to every real game.

Straight three-point eye space

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The outside is closed. Black has only D5, E5 and F5 in a straight line inside; the middle point E5 is vital.

Black makes eyes first

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Black E5 first splits the space into two independent true eyes at D5 and F5. The entire group can live.

White plays the vital point first

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If White takes E5 first, Black loses the vital point for making two eyes. Black at D5 is captured by White F5; Black at F5 is captured by White D5.

Original lessons by Yiban ·