OC, play depends upon the details of White's territory. This agrees with mitsun's analysis.
White's reverse sente gains 3 2/3 points.
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| Frequent Yose Position - Which is the Better Move? http://www.lifein19x19.com/viewtopic.php?f=15&t=2297 |
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| Author: | Dusk Eagle [ Wed Nov 03, 2010 11:57 am ] |
| Post subject: | Frequent Yose Position - Which is the Better Move? |
I have a yose question about a frequent yose position. Below is an easy-to-understand tesuji for white: However, if we remove the marked stone, and assume the area on the right is white's territory, which is the better move for white: a or b? With 'a', the game will obviously go like this: Counting the squares as positive points for black and the triangles as negative points for black, we get a tally of -3. However, the throw-in seems more complicated: Let's say that white does not need to worry about getting cut at 'a'. The value of playing first in this position seems rather low, so both players will probably play elsewhere. However, eventually this position will become the biggest place to play, and I can't figure out exactly what the value of this position is. It seems both players have too many options for whether to respond to their opponent's move or not. I'm still learning miai counting, and this position just blows me away. So, can anyone show me which move (the block or the throw-in) produces a better result for white? |
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| Author: | Chew Terr [ Wed Nov 03, 2010 12:03 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Didn't a similar position appear in a Malkovich game about a month ago? |
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| Author: | daniel_the_smith [ Wed Nov 03, 2010 12:03 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
This seems like the best white could possibly get this way and by my count is one point worse than simply blocking. |
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| Author: | Magicwand [ Wed Nov 03, 2010 12:08 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
final answer... below is the correct move. and usually throwin will yield better result for white. |
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| Author: | mitsun [ Wed Nov 03, 2010 1:53 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
If we assume the area on the right is white's territory, then W should be able to capture the B stones without a geta, since B runs out of liberties when he eventually hits some W stones or runs into the edge of the board: But if B simply captures the W throw-in, W cannot block without risking ko: Assuming W is unwilling to risk this ko, this will be the result. The last two moves can be played later, but can be assumed sente for B. This result is several points better for W than the reference position, where W blocks immediately. B actually does better to sacrifice a second stone: This is the likely final position, after each side captures two stones. The final point count is the same as the reference position, where W blocks immediately. Reference position: Suppose B just descends, presumably in sente. The final result is two points worse for B than the reference position. Conclusion (unless I am missing something) -- B should hane, W can either block or throw-in. If W throws-in, B should sacrifice two stones. |
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| Author: | Dusk Eagle [ Wed Nov 03, 2010 2:05 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Thanks everyone! Chew Terr - I vaguely recall something like that, but I haven't followed Malkovich games for a long time, so I don't know for sure. |
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| Author: | Harleqin [ Wed Nov 03, 2010 3:49 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
mitsun wrote: This diagram is wrong. There is one white stone too much: Therefore, this is one point better for White. |
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| Author: | HermanHiddema [ Wed Nov 03, 2010 3:51 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
mitsun wrote: This is the likely final position, after each side captures two stones. The final point count is the same as the reference position, where W blocks immediately. Where did the marked stone come from? |
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| Author: | Bill Spight [ Wed Nov 03, 2010 4:43 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
OC, play depends upon the details of White's territory. This agrees with mitsun's analysis. White's reverse sente gains 3 2/3 points.
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| Author: | mitsun [ Thu Nov 04, 2010 12:47 am ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Harleqin wrote: This diagram is wrong. There is one white stone too much ... Thanks for the correction. The correct play makes more sense now -- B should hane, W should throw in, B should give up 2 stones. I refuse to count 1/3 points, so I will trust Bill on the value of the position
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| Author: | Bill Spight [ Thu Nov 04, 2010 8:02 am ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Small note: It does not matter whether Black throws away two stones, three stones, or more, the final score will be the same. Not so small note: If Black captures the throw-in stone immediately, she should be able to win the ko. Therefore White should avoid the ko, and then the score will be the same as when Black extends instead. (Yose books generally assume that Black can win such kos. In this case, however, the loss of the ko is huge for Black. That is why extending is optimal for Black. The immediate capture assumes that Black can win the ko and that White will make a mistake. Larger note: If  is correct, then  is wrong. White should atari at 2 instead.
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| Author: | emeraldemon [ Thu Nov 04, 2010 8:16 am ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Chew Terr, You may be thinking of this position in my game vs tj86430: In the game, play went this way: If I understand the thread correctly, it doesn't exactly fit this situation, because of the atari, as dusk eagle pointed out in my game: So it seems the best play there was this: |
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| Author: | Chew Terr [ Thu Nov 04, 2010 8:19 am ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
emeraldemon wrote: Chew Terr, You may be thinking of this position in my game vs tj86430 That's the one, thanks! Not being able to remember was going to bother me. =) Now, to compare the two and try to see how much I can internalize to actually use. Endgame is hard. |
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| Author: | Bill Spight [ Thu Nov 04, 2010 8:41 am ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Dusk Eagle asks about the value of this position: I have added some stones to make it clear that White has territory to the right and that there is no threat of a cut at "a". Let's count the final score as 0. is gote. Now from this position suppose that Black plays first.  takes back.The final score is -1, i. e., 1 point for White. Now suppose that White plays first:  takes the ko.If Black wins the ko the result is -1, if White wins the ko it is -2. So the count of this position is -1 1/3. A play gains 1/3 point. And the count of the original position is -2/3. A play gains 2/3 point.
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| Author: | Bill Spight [ Thu Nov 04, 2010 9:02 am ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Here is what I get for the interesting position in emeraldemon's game: is a 4 1/6 point sente (assuming that Black cannot stand the ko).Next,  (or a White play at 1) gains 1 5/6 points.Next, (or a capture by Black) gains 1 1/3 points.
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| Author: | topazg [ Thu Nov 04, 2010 9:08 am ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Bill Spight wrote: is a 4 1/6 point sente (assuming that Black cannot stand the ko).Next, (or a White play at 1) gains 1 5/6 points.Next, (or a capture by Black) gains 1 1/3 points.    
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| Author: | Bill Spight [ Thu Nov 04, 2010 9:24 am ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Bill Spight wrote: Here is what I get for the interesting position in emeraldemon's game: is a 4 1/6 point sente.Oops! I goofed.  Black should throw in at  . After  the next play gains 1/3 (Black will capture the three White stones in the process).So the sente is worth only 3 2/3 points. Edit: I see that there are additional complications, but I have to run now. OK, I'm back. Well, I goofed all right, but not in the way that I thought. On the assumption that I originally made, Black cannot stand this ko (which also arises if Black plays at  ). So I got the right answer the first time.Let this be a lesson to me.  Just because you get the right answer doesn't mean you're right. Be thorough.
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| Author: | ndkrempel [ Thu Nov 04, 2010 5:28 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
You didn't show the variations when black plays first and white tenukis. Can't black go on to capture 3 stones in gote by exploiting the life&death issue of the corner? Doesn't that make it more than 4 1/6 points sente? |
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| Author: | ndkrempel [ Thu Nov 04, 2010 5:32 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Ok, on reflection I don't think black can capture any stones, but seems like black can gain a couple of extra points beyond the obvious ones, so still worth looking into the variations when black plays first and white tenukis. |
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| Author: | ndkrempel [ Thu Nov 04, 2010 5:42 pm ] |
| Post subject: | Re: Frequent Yose Position - Which is the Better Move? |
Ok, apologies for the multiple posts, but thought I should put some substance to my comments. Here is the best I can see for black playing first: (The final move is to avoid a seki.) Note that black got the 7 move in sente here, which he doesn't get in most variations where white has played 5 first. |
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