| * | Determining life and death | |
| Dia. 1. The black group in the corner has two eyes and is alive. Let's look at similar shapes in Dia. 2 etc. |
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| Dia. 1 | ||
| Dia. 2. The corner black group has only one eye, so its life or death is undecided. Dia. 2A. If White plays first at 1, Black dies. On the other hand, if Black plays first at 1, he will live. As a go proverb puts it, 'the enemy's vital point is my vital point'. |
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| Dia. 2 | Dia. 2A | |
| Dia. 3. The status of the corner black group has not yet been decided. Dia. 3A. If White plays first at 1, the black group dies. On the other hand, if Black first plays a stone at 1, he will live. |
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| Dia. 3 | Dia. 3A | |
| Dia. 3B. White 1 fails, as it misses the vital point. If Black captures the white stone, his group lives. |
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| Dia. 3B | ||
| * | Dead stones | |
| Dia. 4. The corner black group is already dead, even if Black plays a stone. Stones with no breathing spaces are dead, of course, but stones that cannot avoid being captured are also considered dead. Dia. 4A. The corner black group has no chance of escaping. There is no need for White to play the marked stones and actually take the group off the board. These moves would actually be a minus for White, as they reduce his territory by three points. |
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| Dia. 4 | Dia. 4A | |
| * | Pointless invasions | |
| Let's look at White's territory in the situation above. The white group has five points of territory and is alive, of course. Dia. 5. Black invades White's territory with 1. This move is meaningless, as it has no effect on the life and death of the white group. White just ignores it. If Black next plays at 2, this is atari against six white stones, so White will capture the two black stones. Black 1 is a pointless invasion: Black just loses one point outright. |
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| Dia. 5 | ||