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Semedori example 2
Path: PleaseReviewMe · Prev: 44PointLowApproach · Next: Priority
Keywords: EndGame
Jan: I couldn't visualize semedori until I came across this tesuji in The Endgame. I hope I've explained it properly.
In the initial position, if Black plays a White will lose two stones. Something has to be done.
The obvious play at
Comment: By doing this the hane remains (or becomes?) Black's sente, and Black will probably get to play it, so that eventually the situation will look like the next diagram:
If we just count the points along the sides (the area around White's finger is assumed to be dame) Black has 6 (circled) points, and White has 7 (squared) points, i.e. one point for White locally. However, White can do better:
White throws in a stone at
Comment: Less forced.
However Black's hane at a no longer works because of shortage of liberties - a connection one point to the left of a would be an auto-atari, so Black would have to play something like the next diagram if he were hell-bent on that hane (playing
Which seems like gote to me. However because of a snapback, White can descend to Charles No snapback, I think.
Jan: You're completely right. But then I'm at a loss to give a short reason why
GoranSiska Do you need one?
Bill: Two things about W 1 below: First, it's not sente, it's ambiguous (assuming that Black is not komaster). Second, it's dominated by the atari at
Jan: That goes a long way to explain why I couldn't argue for Bill: Well, as I have said, saving the two white stones is not sente. Jan: (Sorry Bill, I didn't read the diffs properly so I missed your first comment; but I didn't say that the first play by White was sente...) Aaargh! Is nothing in the endgame ever simple? Anyway, I was paraphrasing The Endgame without really thinking things through. It made sense to me that this was an example of semedori, I wasn't considering whether and when White would want to play here in the first place.
Maybe my comment at the 'Too simple' diagram should read 'When the time comes, the obvious play at
Also I'm not 100% sure if we're referring to the same
If we now count the score, Black has 5 points (three circled points plus two for the circled White prisoner), however White has 9. Local count is therefore 4 points for White, 3 points better than the first way of playing! One point of this can be attributed to the fact that Black had to capture the single White throw-in stone using two stones (that's the semedori bit), and the other two points come from the fact Black's hane is no longer sente. [1]: On a real board, it's easier to see :-)
(Here we are assuming that Black cannot afford to make ko.)
As a 1 point White sente, this is a tiny in chilled go.
The descent,
This position is a 0|tiny in chilled go, with an atomic weight of 1. It is positive, which means that it gives Black an advantage in the fight for tedomari at temperature 1. Black has three chances to get the last play at that temperature. First, he can fill at 1. Second, he can fill at 2 if White plays at 1. And third, he can take back if White captures at 2. See infinitesimals and playing infinitesimals. Path: PleaseReviewMe · Prev: 44PointLowApproach · Next: Priority This is a copy of the living page "Semedori example 2" at Sensei's Library. ![]() |