Lesson7

SOME BASIC TSUME-GO

By now we already know that a capture can be avoided by making more liberties. But when is impossible to get more liberties we have to make two eyes (see "Basics1"). Still is important to know the minimum number of liberties we need to build two eyes and some basic, useful shapes.
			In this position black has definitely one eye in the corner (in 1x1) and is surrounded by white. With black 1 he's trying to build another eye. What should white do?.

			Blocking at 2 is completely surrounding black but playing at 3 completes the second eye black needs so he is alive.

			White should play like this and the eye at A is fake so black dies.

			This is a simple life & death problem. Black has just played at 1 so white to move and kill.

			White 2 is correct. Now black has to play at 3 AND 4 to make life but that's impossible, so he dies.

			White 2 is wrong! Playing at 3 helps black to make 2 eyes so he escapes.

			Another simple problem. White to play and kill.

			Wrong answer! Black has two eyes after playing at 3.

			White 2 here is correct! Even if black captures at A he only makes a fake eye! So sacrificing a stone can destroy the opponent eye in some shapes!
			White to move and kill. Again a sacrifice is needed.
			Sacrificing at 2 and 4 is the answer. Black has only fake eyes.
			This is a variation but black dies after white 6 (played at 2). This is an example of multiple sacrifice ending with black's death.
			White to move and kill. Think of sacrifice again!
			This is the right answer. Please remember this useful technique!
			Wrong! Black is alive now!
			Wrong sacrifice this time...
			White 2 here is correct! Even if black captures at A he only makes a fake eye! So sacrificing a stone can destroy the opponent eye in some shapes!