Game 401439

final position (dead stones marked)  

White: hexkid (19 kyu)
Black: myrddin (19 kyu)
komi: 8.5

White needs one more move at the marked point.

Moves 1 to 10  

Moves 11 to 20  

Moves 21 to 30  

hexkid: W4 -- I counted myself (White) some 20+ points behind, so I had to try something more active.

Moves 31 to 40  

Moves 41 to 50  

B5 captures a stone
B9 captures W4

Moves 51 to 60  

Moves 61 to 70  

unkx80: At first, I thought Black is going to win this game...

Gronk: a is the vital point for Black.

hexkid: While I was playing the game a didn't worry me too much because I thought I could make b a half eye. I regarded a and c as miai.

Gronk: Keep reading. Consider Bd after Wc. I believe B can get an eye at the edge if White tries to take the one at b away with Wc. It takes some reading and it is always possible I missed something. Nevertheless, B should have lived in the center and had many chances to do so. It makes for an easy victory.

unkx80: If you don't mind some more advanced material, take a look at [1].

hexkid: No, I don't mind it at all. Thank you.

Moves 71 to 80  

Gronk: For example, Ba works now. W10 at c is trickier to read and results in miai for an eye at the edge or at b, if I am reading correctly. Details omitted.

Moves 81 to 90  

unkx80: But Black gets his liberties all filled up. As a result, Black loses the capturing race instead.

And hey, B9 displays atari-blindness!

Gronk: Now it should be clear that W10 takes the vital point.

hexkid: And B5 at a now would make the group alive, I think.

Gronk: No need to guess. My advice: Prove it to yourself that B needs W10 too. If B is unconditionally alive then W can never remove it from the board. If needed, put stones to board to see for yourself. Then try to visualize it in your head.

hexkid: I had to try a few variations on CGoban2 to see that. Thank you Gronk.

Gronk: Good for you! The best way to progress is to do the analysis yourself on a board. Based on what you've shown here, some review of life and death would be beneficial. There are good problems on SL to help. See BeginnerExercises.

Walin: B5 at W10 on the other hand lives, as white can't play at a next due to shortage of liberties. So as Gronk pointed out W10 is the vital point.

Moves 91 to 100  

Moves 101 to 110 (8: pass)  

Moves 111 to 118  

[1] unkx80: Below is some advanced advice for you, if you can see why, then it is good, if not, you can always come back again later. Just don't feel bad about it. It is regarding move 65.

hexkid: Thank you for a very clearly written material. When I was playing I remember thinking about the safety of these key stones but figured they were safe. My opponent didn't see it either and if it weren't for you, I'd be one important point poorer. Thank you.

Move 65  

Black 65 was at a. If Black plays at B1 instead, then the white+circle stones get captured. I will attempt to show you why later, but be aware that a lot of detail has been omitted. Note that these white+circle stones are key stones, so when they are captured, then the middle Black group gets connected to the upper left Black stones all the discussion about the life and death of the middle Black stones becomes moot.

Move 65  

If W2, then B3 captures in a net. Similarly, if W2 at a, then Black plays B3 as well.

Move 65  

If W2 here, then B3 simply blocks. The capturing race is three liberties for Black to two liberties for White, so Black wins this capturing race by one move.

Move 65  

The tricky move here is the atari at W2.

Move 65  

The connection at B3 here would be a mistake. Then W4 blocks. Note that B5 cannot play at W6. So if B5 atari, then W6 connects. Black loses this capturing race (why?).

hexkid: The black group has two liberties, the white group has three liberties. If Black plays one point below B5 his group has three liberties, but White goes first and wins the capturing race. Playing two points below W4 also doesn't help.

Move 65 (6 at marked Black stone)  

The solution is actually to atari at B3 and B5, forcing W4 and W6, and then blocking at B7. Note that if B3 is at B5 instead, then White connects at B3 instead and White wins the capturing race (why?).

hexkid: Why? Hmmmm ... I'll need to get home and fire up CGoban2 ...
Blacks gets three liberties, White also has three liberties (and a Black stone in atari) but Black gets to play first. Maybe he can play at a and ignore the stone in atari ...

hexkid: (later) Ah! It's easier with a board to try variations on.

Move 65  

Finally, if W8 hane, then B9 atari, followed by a.

hexkidGame401439 last edited by ProtoDeuteric on August 2, 2006 - 23:44
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