Beginner Exercise 194 / Solution

Sub-page of BeginnerExercise194

Solution in simple terms


The best play for Black is to play elsewhere. Recognizing that playing elsewhere is an option gets full marks for this beginner exercise.

Nonetheless, the fact that Black is not able to obtain unconditional life makes it a failure diagram in Beginner Exercise 191.

See further comments below for an advanced analysis.

Analysis at the beginner level


Obviously, B1 here is death in gote, since a White move at either a or b almost fills the Black group into a bulky five dead shape.


It should be recognized that for Black to obtain unconditional life, Black must start a ko at B1 and win it. However, W2 will take the ko first.


On the other hand, if White must kill the group, then W1 must start a ko. In this case, Black will take the ko first at B2.

Hence, this ko is unfavourable for either player.


Of course, W1 has the option of making seki. But Black lives this way.

Further comments

Going further into advanced material, one should then see that the situation in this problem is actually some variant of a ten-thousand year ko, in which neither player wants to start the ko too early in the game.

However, these things are paradoxical. If White is komaster, Black should often start the ko, even though he loses it. The point is that he gets a play elsewhere while White wins the ko. If he waits, then the value of that play will probably diminish.

Things are more complicated when Black is komaster. If other plays are worth enough, then White should normally start the ko for the same reason that Black should when White is komaster. Then there is a temperature range where neither side will typically want to play, and then at lower temperatures each side will want to play because White now threatens to make seki.

Beginner Exercise 194 / Solution last edited by Unkx80 on December 28, 2005 - 11:40
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