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More endgame shenanigans http://www.lifein19x19.com/viewtopic.php?f=15&t=3148 |
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Author: | jts [ Sun Feb 06, 2011 1:28 pm ] |
Post subject: | More endgame shenanigans |
All of the posts lately about the endgame have made me realize that my endgame is... slovenly, to say the least. I thought that I would practice concentration and patience by making myself endgame problems drawn from real games. I have no idea whether this will be helpful or not, nor whether the problems will be too easy, too hard, or just plain boring. (Actually, "boring" isn't a huge con, since I wish to learn to focus.) But if anyone wants to play along, please join in! I'll post the answers (that is, how the game actually went) once I've tried to solve them all. The problems are "best play for each side," not to win. Endgame Problem #1
Endgame Problem #2
Endgame Problem #3
Endgame Problem #4
Endgame Problem #5
Endgame Problem #6
Endgame Problem #7
Endgame Problem #8
Endgame Problem #9
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Author: | jts [ Sun Feb 06, 2011 3:32 pm ] |
Post subject: | Re: More endgame shenanigans |
My first attempt:
I think I'll count "e" as black's 1 pt sente (the ko is very, very heavy for W... unless it's 100% W wins kos, I think he needs to respond). "c" is a 1 pt move with a 2pt follow-up for W. "a" is a 1 pt. move which I think has a much bigger follow-up for W (about a 5 pt. sente?), whereas if B plays at "a" the follow-up is 1pt with a ... 1.5 pt follow-up? This is all to get around to "b"; if B plays B, it's a 1pt gote, whereas if W plays it it's a 1 pt gote with a 9 pt followup. Because it has such a big follow-up, I'm pretty sure that any Black move except "a" can be ignored to play "b". The move at "d" looks like a 1 pt with a 3 pt followup. This is harder than I thought it would be; I was a little worried that the temperature would be extremely low and there would be no interesting choices. So, I think it should go something like this:
That took me around 20 minutes, and I still need to count to see who wins. I think I'll check the correct sequence after I've done more of the problems. |
Author: | snorri [ Sun Feb 06, 2011 3:35 pm ] |
Post subject: | Re: More endgame shenanigans |
Whose games are these? |
Author: | topazg [ Sun Feb 06, 2011 4:40 pm ] |
Post subject: | Re: More endgame shenanigans |
#1
I read "a" as 2 points gote. "b" as 1 point reverse sente. "c" as 2.5 points gote. "d" as 1 point reverse sente, "e" as complicated. If White ignores, the capture is dangerous. White must play T15, allowing Black to play T19. So that's 5 points if Black gets to connect, and at least 3 points, but in gote. I'll throw 4 into the wind as my guess, and play as follows:
Black wins by 0.5 in mine, loses by 0.5 in yours. However, I don't claim perfect play by any means, and I spent about 90 seconds on the board. ![]() ![]() |
Author: | topazg [ Sun Feb 06, 2011 4:45 pm ] |
Post subject: | Re: More endgame shenanigans |
#2
No other moves worth points? |
Author: | topazg [ Sun Feb 06, 2011 4:55 pm ] |
Post subject: | Re: More endgame shenanigans |
#3 Are there any points left ![]() #4
"a" is sente for White, else it's a truly horribly heavy Black ko. "b" is also very sente. On the offchance that White is ko monster, we can play "b" first, and leave "c" and "d" as mutual kos (you're gonna get one each)
Can't see any other points. #5 Again, no points left? #6 A single half point ko:
![]() ![]() ![]() ![]()
Can't see any more ko threats. ![]() |
Author: | jts [ Sun Feb 06, 2011 5:05 pm ] |
Post subject: | Re: More endgame shenanigans |
snorri wrote: Whose games are these? They're recent pro games. |
Author: | topazg [ Sun Feb 06, 2011 5:35 pm ] |
Post subject: | Re: More endgame shenanigans |
#7 Single 4 point gote capture #8
"a" is an interesting point. That ko is frightening for Black, and White stands to lose very little, so depending on Black's threat level, I expect Black has to connect, allowing White to play "e" for another ko. Why is this useful? Because there are two half point kos at "c" and the "d" area. "b" is a point in sente. So I suspect White will take this point, then "a", then "f". Black plays "g" to prevent White getting the point as White cannot yet play "d". White captures at "e", Black takes "d", White connects a ko, Black takes a ko, and then they connect one each.
#9
"a" is always bigger than a half point ko - In this case, it's kinda huge, because White getting "a" and "e" gives Black a liberty problem. So, I predict after "a", Black will take the remaining point at the top with "b", White will capture at "c", forcing Black to connect at "e", White connects at "a", Black ataris at the top, White connects, and Black plays out the shortage of liberties at "d". White cannot play there first because of the threat of Black "f", creating a ko that White cannot really win:
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Author: | jts [ Sun Feb 06, 2011 5:39 pm ] |
Post subject: | Re: More endgame shenanigans |
My (almost certainly failed) attempt at #2
This problem is confusing because it doesn't look like there are ten moves left (all of these diagrams are about a dozen moves before the end of the game). I looked to see if W could get a seki with a play around "a" (no), and then there's yose at "b", and that's it. If it were W to move I would assume that W plays "b," and then there's a short ko over the last point. But since it's B to move this game must be area scoring. (So far assuring myself that there are no plays under Japanese rules has taken about 10 minutes.) No, the more I think about it... there are too many dame and ko threats for this to be close to the end of a ko fight or dame-filling. I'm befuddled. Maybe I messed up the diagram. I'll check this when I finish the others. Anyway, my solution:
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Author: | jts [ Sun Feb 06, 2011 5:43 pm ] |
Post subject: | Re: More endgame shenanigans |
Wow, topazg has powered through these problems already. I'm going to post the solutions for him, although I probably won't look at any of them until I finish. Just as a warning, all nine solutions are under the hide tag.
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Author: | topazg [ Sun Feb 06, 2011 5:43 pm ] |
Post subject: | Re: More endgame shenanigans |
Ah. These are area scoring? This makes quite a difference ... ![]() |
Author: | topazg [ Sun Feb 06, 2011 5:50 pm ] |
Post subject: | Re: More endgame shenanigans |
Hmmm, I missed ![]() ![]() ![]() ![]() ![]() Still, many thanks for posting ! |
Author: | jts [ Sun Feb 06, 2011 5:56 pm ] |
Post subject: | Re: More endgame shenanigans |
topazg wrote: Ah. These are area scoring? This makes quite a difference ... ![]() I was actually under the impression that they were almost all territory scoring, since most of the names were Korean and Japanese. But (stupidly) I didn't keep the data about ruleset, prisoners, or final score, which were stripped out by the .sgf converter. I'll add it back in when I finish the problems. |
Author: | jts [ Sun Feb 06, 2011 6:06 pm ] |
Post subject: | Re: More endgame shenanigans |
topazg wrote: Hmmm, I missed ![]() ![]() ![]() ![]() ![]() Still, many thanks for posting ! Oh gosh, I screwed it up. Sorry about that. Sigh. I guess I'll have to fix the problem diagrams and then wait a week to forget the solutions. Anyway, glad you enjoyed them. |
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