Beginner Exercise 13 / Solution

Sub-page of BeginnerExercise13

Solution by lavalyn 17k:

It's easiest to make eyes in the corner  

Black B1 takes the corner for eye space. Now the best White can do is to minimize the eye space available, but the available space is sufficient to ensure life.

Full diagram  

For your viewing pleasure, some failure diagrams:

Extending in the wrong direction  

Black, in his attempt to take more of the side, loses after W2 and W4: on the second line, six die but eight live.

What's wrong with white trying W1 here?

A kill for white?  

It seems that black must ultimately play to the right of W1, but he cannot avoid filling in his own eye:

Find an eye  

and black's right-hand eye is falsified. The same will be true if black plays B1 at B3 instead:

Outflank white?  

and black dies as before. How can black respond?

--satyreyes, unknown rank but probably very, very low

Thanks for the present  

Bill: If W1, B2. Then if W3, B4, etc.


rokirovka: As a beginner, I find it helpful to show the shortest variation that proves the black group is alive. B4 threatens to create two eyes in the corner. White plays W5 to reduce Black to one eye in the corner. But now Black plays B6 capturing W1 and W3. After W7, Black plays B8 at W3, creating a second eye at W1, and the black group has two eyes and lives. If White plays W7 at W3, Black plays B8 at W7 and lives.


Also, I find it helpful to show the shortest route to life for Black if White plays at W1. Black cannot play on the first line immediately: If B2 at B6, W3 at W7 reduces Black to one eye in the corner, and if B2 at W7, W3 at B6 takes away the point Black needed for his second eye. So Black extends along the second line with B2, threatening to play next at W3, which would guarantee unconditional life in the corner with a straight five. So W3 is the only try to kill Black. Then Black extends again with B4, again threatening to play next at W5 with a straight six and certain life. So W5 is the only try to kill. Now Black can finally play on the first line: B6 threatens to play at W7 and make two eyes in the corner. W7 reduces Black to one eye in the corner, but now B8 captures W3 and W5. After W9, B10 at W5 makes a second eye and Black lives. If White plays W9 at W5, B10 at W9 also makes a second eye and lives.

So it seems to me that if White had a stone at W9 in the original diagram, W1 would kill. White could then play W9 at W5, and Black is dead with only one eye in the corner.


Elgoran?, 16k: Actually, Black can and will play B2 after W1. Playing W3 just gives Black another prisoner because of B4. If White a, Black b and vice versa.

For your further viewing pleasure, some not so minor changes to the problem (by Sergio) :

Black is dead  

If the white+circle stone is on the second line (instead of the third) Black is dead...

But what should White play in answer to a ?

Killing move  

Even if it's not a clear move to beginners W1 is the only one that kills.

Deebster: Doesn't b kill Black too?

unkx80: Yes, b kills too.

White kills  

If Black plays at a, White kills by the throw-in at W3.

White kills 2  

If Black attempts to capture with B2, White plays W3 to prevent an eye at W1. If Black captures at B4, White plays at W5, the vital point of the remaining straight three.

White kills 3  

But what if Black plays B4? White plays W5 to take away the last chance for an eye. Capture B2 any time to kill the group.

So we can conclude that in the original problem, Black's threat of escape along the second row is necessary for survival. With white+circle present, that threat disappears, and White can hane with impunity.

what about this 1?  

fred : would Black live with B1? And is the rest realistic?

Charles No, W2 should be at B7.

k, i get it

Beginner Exercise 13 / Solution last edited by Elgoran on April 2, 2016 - 13:08
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