How is your positional judgement? Game 20

[Bill Spight]

Assuming area scoring with 7.5 pt. komi, after Elf estimates a winrate of 90% (49.1k playouts) for one player. Which player is it?

$$Bc White to play
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Click Here To Show Diagram Code

[go]$$Bc White to play
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$$ ---------------------------------------[/go]

Enjoy!

[Knotwilg]

Although Black's upper left is an old joseki not to the liking of AI's, on the right hand side, Black has such a good position that I can't see how White would have the upper hand overall. I'll take Black any time

[Tryss]

Before Katago : I prefer white as it has more potential, and with the next move, he can probably nicely stabilize his stones on the right side to erase the potential on the right.

Katago : it agree with me (yay ), and give white +11pts/77%wr

[jlt]

This one is not easy. Black is leading in terms of territory and has no weak groups. White has more influence, but has to take care of his weak group Q6, so I prefer Black.

[Kirby]

Intuition says that black seems good.

[bernds]

First thoughts were that the bots wouldn't like Black's joseki choice in the top left, and the shape in the bottom right looks a little strange. Black has two stones on the second line and White has none.
But even if White were to turn the entire frameworks at the top and on the left into territory - which seems optimistic - it's hard to see how the count would be much more than even. Plus, there are two weak white stones in the bottom right. Presumably the next move will strengthen these, but one move won't even turn them into a secure group, so I'd expect Black to take more profit from the attack.
So, Black it is.

[Bki]

My first instinct is black : he has solid territory, some potential to develop and a weak group to attack. That said, white has a nice position on the left and the top isn't bad either if a bit open. And white has sente.

With sente white can play an extension on the right and black lose his attack target. Maybe he can bully that group a bit for some territory on the right but that's all. Then an invasion of the left looks big. There's a lot that can be done there. Whether to play first on the side or to attach against the shimari is a good question. Or maybe black should be satisfied with a reduction, getting sente to invade the top? The left seems bigger though, and with more potential of development.

Actually maybe the cap at E10, or the knight move at E9, followed by the B4 prope might be a good way to deal with the left.

Then I feel that black wouldn't have a bad game.

[TelegraphGo]

There are no glaring tactical inefficiencies, except maybe a little bit black's bottom right corner. Then for strategic efficiency, W's influence is coordinating well (especially if you can imagine moves getting played at G15 area), while B's influence is about to be nullified by a difficult-to-attack white group on the right. So, without much deep thought, I like white. Edited because I forgot to hide

[xela]

Interesting, this one I feel strongly that I should stay with my "at a glance" assessment and reading won't help (in contrast to that pesky game 19). At least, not for my reading ability :-)

White just feels bigger. Yes, black has a fair bit of solid territory, while white's frameworks are invadable, but white's stones look to me like a textbook example of efficiency. Apart from those two stranded on the right, which are too heavy to sacrifice. But it's white's move, and there's plenty of space around, so it shouldn't be too hard to settle those stones.

I do have trouble choosing the next move though:

$$Wc19
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Click Here To Show Diagram Code

[go]$$Wc19
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$$---------------+[/go]

'a' feels like the safe move, whereas 'b' does more damage to black's framework but is maybe too greedy. Which move I'd play would depend on my mood on the day (possibly on how afraid I am of my opponent!)

OK, now that I've tried thinking for myself, let's see what some bots think.

KataGo: on my machine, it agrees with what it told Tryss :-) W+11, 77% winrate. LZ-242 says 83%, and LZ-ELF says 91%. 20,000 playouts in each case. Nice to see a consensus amongst our expert advisors.

All three prefer 'a' as first choice move:

$$Wc19
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Click Here To Show Diagram Code

[go]$$Wc19
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$$---------------+[/go]

'b' doesn't rate a mention; 'c' is a close second choice (same evaluation as 'a' but less than a quarter of the playouts) and 'd' gets a cursory glance (same evaluation as 'a', only a few hundred playouts). When I put 'b' on the board, it's suboptimal but still good enough to win (2% winrate drop or 1 point loss according to KataGo, 3% drop for LZ-242, 5% drop for LZ-ELF).

[Knotwilg]

Some variations of mine, after seeing my judgment was wrong, and one variation by LZ:

[Uberdude]

I think whole game tewari with my Elf hat on is a better judge than static positional judgement so here is a plausible sequence of play with my Elvish commentary.

Top right has the same weird "was it a shoulder hit to 3-3 and they blocked but then didn't hane" weird shape from game 12, in which Bill revealed it was the result of an initial 6-4 stone so let's say it was that. So Elf thinks 1 is quite bad (-12% before), 2-4 ok, 5 and 6 a little slow but equally so. 7 is good, bots like low approach to 3-4 (but probably closing top right more, maybe that corner actually happened before top left). 8 locally a bit bad (prefer to defend on left to prevent press) and globally more so as entering top left bigger, but then 9 is worse (press or tenuki better), 10 is ok. So black lost in this corner so far

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Click Here To Show Diagram Code

[go]$$Bc
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11 is definitely smaller than top right shimari, and locally probably slow this early in opening (but maybe it was later). 12 is too slow, and side move which bots don't like, 13 likewise, but probably a bit worse as white's side move does help defend against a weakness of group at top left (now that black slid to take corner) whereas black's is pure points. But now at least I have a white sente to go into the top right. In the last game both players made fair sized mistakes in this sequence, but the net effect can be simplified as the sticks of 3 stones are basically even but then black's r14 should be a hane not extend so let's say -10%+.

$$Bcm11
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Click Here To Show Diagram Code

[go]$$Bcm11
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20 for 21 is then a good exchange for white, event though black is building 4th line territory, 21 is just a points move as the 4 stones are already alive (white's follow up at r14 is gote, has cuts and black corner still happy), whereas 20 is important for strength of white's stones and avoiding too much shortage of libs pain. Would a pro really play 21 though rather than invade the top and attack the wall? 23 then slow? 24 a shoulder hit reduction a bot classic, 25 is a weird move we don't see bots play so presumably bad, 26 for 27 a nice little exchange because 25 didn't add libs to r5, and now white has sente and knight move at o7 to run away looks reasonable. So white leading.

$$Wcm20
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$$ +---------------------------------------+

Click Here To Show Diagram Code

[go]$$Wcm20
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$$ +---------------------------------------+[/go]

[Kirby]

It’d be an interesting stat to see how the actual game results correlated with Elf’s assessment, aggregated across all of these games.

These are all pro games, so I wonder how often the end result matched up such that Elf’s favored player won.

[Bill Spight]

In this case the player favored by Elf won the game.

[Kirby]

In this case the player favored by Elf won the game.

Whoops - I guess I’m posting in the wrong thread (should’ve been the main one)..

[Bill Spight]

In this case the player favored by Elf won the game.

Whoops - I guess I’m posting in the wrong thread (should’ve been the main one)..

That's OK. Message received. I'll take care of it.