I like this one, too.
Black to play.
Black's textbook play loses 17½% to par, according to Elf. Assuming komi, as always.
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| Opening problems for AI: Problem 28 http://www.lifein19x19.com/viewtopic.php?f=15&t=17635 |
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| Author: | Bill Spight [ Sat Jul 11, 2020 10:42 pm ] |
| Post subject: | Opening problems for AI: Problem 28 |
I like this one, too. Black to play. Black's textbook play loses 17½% to par, according to Elf. Assuming komi, as always.
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| Author: | Uberdude [ Sun Jul 12, 2020 12:30 am ] |
| Post subject: | Re: Opening problems for AI: Problem 28 |
I don't know what the textbooks say (q14 to prevent press and threaten invasion?), but confident to predict bots say black should correct his mistake of playing a 5-3 point by closing the corner, per gospel. |
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| Author: | Knotwilg [ Sun Jul 12, 2020 3:16 am ] |
| Post subject: | Re: Opening problems for AI: Problem 28 |
Opening gospel says lower right enclosure, unless another place is more urgent.
White's extension may make this play efficient for her.
How about this exchange? It looks more messy for both. Messy is usually a little better for White, who has komi in the pocket. So I'll go with the enclosure. |
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| Author: | Bill Spight [ Mon Jul 13, 2020 8:27 am ] |
| Post subject: | Re: Opening problems for AI: Problem 28 |
This position comes from GoGoD 1660+c, Honinbo Doetsu (W) vs. Honinbo Dosaku, but it could have come from a modern game.
Dosaku played the ideal 5 space extension from the top left enclosure, leaving the 2 space extension at a towards the bottom left enclosure, or a one space jump at c if White extends to b. This is one of the first things we learn about development from a corner enclosure. It is surprising to learn that it could lose so much in such a simple position. Assuming komi, OC. Doetsu approached the bottom right corner and then Dosaku played the extension at  on the bottom side, which also prevents a pincer against  . But that excellent play seems to be dubious, losing 5% by comparison with d, according to Elf. e and f are also playable. (It would not surprise me if Elf preferred e the next time it analyzed this position. The bots love the press. )
After  pincers, OC. Then Black plays the press in the bottom right corner, followed by his own pincer at  .  makes a small base, continuing the attack. Then, instead of the two space extension at a, Black attaches against the corner enclosure on the 3d line.
After the press in the bottom right,  plays the 3d line attachment in the corner, and then Black stakes out the bottom side. Then  plays his own press in the top right corner. The press is a real workhorse. Top choice: Enclose the bottom right corner
Making a second enclosure is also an ideal textbook play. But before the AI era Dosaku's extension would also have been considered playable. One problem with it is that  at 9 is too good. The 5-3 stone, , cries out for an enclosure.
plays the taisha. OC, a is also playable. plays the slide. Then plays the 3d line attachment against the top left enclosure, and White stakes out the left side.  plays the attachment at b. |
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| Author: | dhu163 [ Sat Jan 01, 2022 3:02 pm ] |
| Post subject: | Re: Opening problems for AI: Problem 28 |
Speculatively: Current position: 1. Of course B must play R4 or perhaps Q5. 2. Is Q15 a textbook move here? I think it is probably one of the best alternatives. Opp to play 1. Of course W should play R3 or R4. I prefer R4 in this position since P3 already splits W's lower side development so R3 doesn't really help (it isn't as if the lower side is B's and R3 helps gain access/life with N3 and P2). R4 helps attack the upper right 3-4 stone too. If not, I would exchange Q15 first before diving with R3 (or perhaps still R4). Past: 1. B has deviated with the lower right 5-3 and W at K17 is weird to compete for the relatively small upper side, especially without having gotten Q15. B has sente to play R4, so B is marginally ahead. Check: 1. of course, but I somewhat expected B to have played on the lower side instead. They seemed to really like creating living groups on the 3rd line back there, slightly disrespecting the D11 and F16 centre reductions. |
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