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| How is your positional judgement? http://lifein19x19.com/viewtopic.php?f=15&t=16909 |
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| Author: | Bill Spight [ Fri Sep 06, 2019 3:05 pm ] |
| Post subject: | How is your positional judgement? |
The bots are showing us that the old ways of positional judgement leave something to be desired. Here is a thread to improve our positional judgement, by seeing how well we can tell who is ahead, according to a top bot.  To get us started, here is a position after  where Elf thinks that one player has an 89½% chance of winning (29k playouts), under area scoring with a 7½ pt. komi. Which player is it? Should be easy, eh?  Enjoy!  Edit: I added to up the playout count.
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| Author: | Kirby [ Fri Sep 06, 2019 4:01 pm ] |
| Post subject: | Re: How is your positional judgement? |
| Author: | mhlepore [ Fri Sep 06, 2019 5:21 pm ] |
| Post subject: | Re: How is your positional judgement? |
| Author: | jlt [ Fri Sep 06, 2019 11:27 pm ] |
| Post subject: | Re: How is your positional judgement? |
| Author: | Uberdude [ Sat Sep 07, 2019 12:21 am ] |
| Post subject: | Re: How is your positional judgement? |
It's easy because I recognize the game (my value network is over-fit) 
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| Author: | Bill Spight [ Sat Sep 07, 2019 3:31 am ] |
| Post subject: | Re: How is your positional judgement? |
Uberdude wrote: It's easy because I recognize the game (my value network is over-fit) Sorry.  You might like my next one, then. Edit: Err, that's like. Typo.
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| Author: | hyperpape [ Sat Sep 07, 2019 7:38 am ] |
| Post subject: | Re: How is your positional judgement? |
| Author: | Uberdude [ Sat Sep 07, 2019 12:01 pm ] |
| Post subject: | Re: How is your positional judgement? |
Just for reference/calibration of the different scales of bots, AlphaGo in the teaching tool (between Master and Zero versions) thinks this position is 67%. LZ 226 too. And LZ 15b-0a96 64%. |
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| Author: | Bill Spight [ Sat Sep 07, 2019 6:17 pm ] |
| Post subject: | Re: How is your positional judgement? |
The first game is one of the Master games, GoGoD 2017-01-03a. White was Yang Dingxin, 5p. OC, it is Black who is ahead, and who won the game. Yang's big mistake, says Elf, is  ,  , a play that we humans had thought was good. As an extension it is a little far from the  stone in the bottom left corner, but it aims at an extension to a, which makes a base and threatens the thin Black corner. (White actually extended to a in the game.) Elf reckons as a hefty 19% point loss. Elf normally devalues early plays on a side, but not to this extent. The reason, I think, is that White had the alternative of the solid connection at 11. If White plays there Elf estimates Black's winrate at 48% with 120.2k playouts. was not on Elf's radar at all, with 0 playouts. So Elf estimates Black's winrate after  at 67% with 28.9k playouts.After the solid connection, Elf as White would extend on the 4th line. Often bots play elsewhere after the solid connection, but not in this case. To get to a White winrate estimate of only 10½%, after White made a number of small errors.The largest of these was the jump attachment,  , instead of the nose attachment at a. The nose attachment has a Black winrate estimate of 68½% with 56.7k playouts. was scarcely on Elf's radar, with only 34 playouts. Elf awarded it the Black winrate estimate after of 77% with 29.9k playouts. lost 8½%. =  This is Elf's main line after the nose attachment. White forms a small group on the top side and makes shinogi in the bottom left corner. The second largest error, in terms of winrate, was  instead of the block at a. White a yields a Black winrate estimate of 89½% with 108.8 playouts. was on Elf's radar, with 1.5k playouts, but has 29k playouts with a Black winrate estimate that rounds to the same figure, 81½%. loses 8%.Elf's main line after the block.
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| Author: | Bill Spight [ Sat Sep 07, 2019 6:21 pm ] |
| Post subject: | Re: How is your positional judgement? |
Game 2. As always, area scoring, 7½ pt. komi. Elf thinks that one player has a winrate of 91½% with 26.3k playouts. Which player is it? Enjoy!
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| Author: | Uberdude [ Sat Sep 07, 2019 9:45 pm ] |
| Post subject: | Re: How is your positional judgement? |
This one's tricky as there are 2 urgent areas so I'd need to play out some possible continuations to reach a quiet position which is easier to judge. But then I'm also judging the possible mistakes in my anticipated sequences. |
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| Author: | Bki [ Sun Sep 08, 2019 1:43 am ] |
| Post subject: | Re: How is your positional judgement? |
| Author: | Kirby [ Sun Sep 08, 2019 5:15 pm ] |
| Post subject: | Re: How is your positional judgement? |
| Author: | Bill Spight [ Mon Sep 09, 2019 5:37 am ] |
| Post subject: | Re: How is your positional judgement? |
Game 2. This was a no komi game between Go Seigen (W) and Mitsuhara Itaro, 7 dan in June, 1950 (GoGoD 1950-06-00b). OC, Elf assumes area scoring with a 7½ pt. komi. From that perspective after  Black has an estimated winrate of 91½% (26.3k playouts). However, it was White, Go Seigen, who won by resignation.BTW, as Uberdude suggested, was an approach to the bottom right corner, resulting in a Kobayashi style joseki there.Note: In reviewing no komi games with the Elf commentary, I have observed that often White takes an inferior position early in the game, assuming komi. OC, objectively things are even worse for White with no komi. It has long been known that with no komi White makes inferior plays in order to create chances, but I was surprised how far White went in that regard. Plainly, the results justified such play. For instance, Go Seigen won this game by resignation. But to develop our positional judgement in the days of komi, we assume a 7½ pt. komi. Therefore, moves that Elf regards as errors by White are not necessarily errors in a no komi game.  is a case in point. As a dual purpose move, it is obviously a good play in a no komi game. So why does Elf regard it as an error? =  Elf recommends the invasion with . This diagram shows Elf's main line.  secures Black's group. Then  - is a flow of the stones resulting in White taking territory on the bottom side. may be an error, even in a no komi game. In the game Black played  at a, but Elf recommends the play on the 3d line, which makes a base with the  stones and forms a moyo with Black's wall to the right. After pushes through the gap, Black plays  with sente and then switches to the 3d line attachment against the top left corner.The main reason I think that in the game may have been a mistake at no komi go, as well, is that Elf treats in its mainline as a double sente (209k playouts). In which case White should have played it right away. is an interesting attack. A pincer, resulting in a run-run to the center, would be bad for Black, given White's strong wall. pushes the fight into the center. Simply taking territory would not be good enough.
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| Author: | Knotwilg [ Mon Sep 09, 2019 5:44 am ] |
| Post subject: | Re: How is your positional judgement? |
Now I will peek at the other comments
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| Author: | Bill Spight [ Mon Sep 09, 2019 6:55 am ] |
| Post subject: | Re: How is your positional judgement? |
Game 3. As always, area scoring with 7½ pt. komi. Elf estimates a winrate of 92.7% (31k playouts) after . Which player is it?Enjoy!
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| Author: | Knotwilg [ Mon Sep 09, 2019 8:59 am ] |
| Post subject: | Re: How is your positional judgement? |
| Author: | Bki [ Mon Sep 09, 2019 9:26 am ] |
| Post subject: | Re: How is your positional judgement? |
| Author: | Bill Spight [ Wed Sep 11, 2019 9:17 am ] |
| Post subject: | Re: How is your positional judgement? |
Game 3. A no komi game between Go Seigen 8 dan (W) and Sakata 7 dan, GoGoD 1950-07-04a. The usual caveats about no komi games apply. For Sakata to take Black with no komi was the usual handicap; given the dan difference Sakata would take White ⅓ of the time. Elf estimates White's winrate at 92½% with a komi of 7½ points. Even with no komi, White, Go Seigen, won by resignation. According to Elf, both players made a number of small mistakes early in the game, which may be explained by the shared beliefs about the opening at the time. The first sizable mistake was  , which may have also been a mistake with no komi. caught me by surprise. When I was learning go the sacrificial hane at 20 was joseki. It appears that allowed White to make too much outside strength with  . The ladder works now, but Black has many ladder breakers near the stones. At the time, 25 was usual, but today's bots have devalued the sides. is good shape. a would allow a double peep.According to Elf,  loses 12½%. OC, the subsequent fight is complicated, and there is no komi, so was not necessarily a mistake. This sacrifice lowers White's winrate estimate to 80%. White sacrifices the corner for central strength. Elf considers Knotwilg's idea for and gives the above variation, with pushing into the corner. Next if Black a, White b, I reckon.The remaining diagrams show the continuation in the actual game. The fight continues into the center.  severely attacks Black's small group in the top right.Since Black lives with sente, he manages to put some pressure on White. White pushes on into the right side. the center battle continues. Elf gives Black a 2% chance to win. Go Seigen won by resignation after White 234. (Sakata hated to resign.) |
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| Author: | Bill Spight [ Wed Sep 11, 2019 9:21 am ] |
| Post subject: | Re: How is your positional judgement? |
Game 4. As always, assume area scoring with a 7½ pt. komi. After Elf gives one player an estimated 88% winrate with 144.2k playouts. Which player is it?Enjoy! |
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. After 
, no group on the board is in great danger. It looks like White leads by 1-2 points (Black 26 + 2 prisoners, White 21 + 1 prisoner + 7.5 komi, this is not very precise because I am not sure about the boundaries) but it's Black's turn. The fact that Black has sente should be worth a few points but his lower group has weaknesses that need to be defended (how does one evaluate that?). So from a human point of view, I really don't know who is leading...
and force 
?