Semedori example

    Keywords: EndGame
Endgame problem  

What if anything can White gain by playing here?

Charles Matthews

A difficult position, Charles!
Looks like White can get a seki or ko to me.


White prepares the cut  

Charles From a game of mine last week. I thought the basic idea was the cut at W3 for White, to gain points. Preparation W1 for B2 is obvious enough. White a for Black b would presumably been White's prerogative.

I didn't see a seki, but perhaps the position isn't exactly as in the game: I simplified it somewhat.

So, B8 caught me a little by surprise. Now it becomes important how many liberties the lower black group has on the outside.

Variation 1  

Bill: White can also start this way, I think. Off to the races. ;-)

Variation 1 (continuation)  

Charles So now Black is in a hurry to play B1? Ah, but now I see that W4 is too naive.

Variation 1 (further continuation)  

DaveSigaty: The approach seems right for Black but B3 here would be slightly better at W4 (see below [1]) perhaps.

Variation 1 (even further)  

And now? Could become a double ko?

Variation 1b  

Bill: B1 is, I believe, tesuji. Now White has nothing better than W2, I think, and the end result should be the same as the main line starting with the cut. But it is complicated.


Variation 1 alternative  

DaveSigaty: After B3 if White plays W4, she is simply captured by B5, so...

Variation 1 alternative  

White has to play W4 and after the sequence to W8, Black can play tenuki. White has achieved a double ko that can provide unlimited ko threats, but in gote.

Variation 1 alternative?  

Chris Goldsmith - I don't understand B5 in the previous variation; surely B should just play B5 here. And then White is dead: a and b are miai for White's death.

Charles (Hi Chris - quite a meeting on Monday!) In that case W4 at B5 will take the eye away in sente (or gain half-a-dozen points). A rare enough case of an intermediate play that works well.

Variation 1 alternative  

In comparison, this W8 threatens to capture the outside ko and connect. Black's capture of the inner ko is not atari on the white stones. Black has to play B9 so White has created the double ko in sente.

Variation 1c  

Bill: With the potential Black eye gone at a, White's next play is, I believe, to atari with W1 and then connect at W3. Through B8 White loses the capturing race, but forces Black to take all the white stones.

Variation 1c (followup)  

W3 - B4 is almost always sente, since Black can rarely afford to let White make a huge ko.

Variation 1d  

Alternatively, Black can connect with B1. Then W2 prevents an eye for Black. B3 wins the race.

Variation 1d (continued)  

Now W1 - B4 is sente.

All roads lead to Rome, more or less.

Semedori example last edited by Unkx80 on April 17, 2004 - 21:21
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