How is your positional judgement?

Bill Spight · #1

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 :b31:

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? :mrgreen:

Click Here To Show Diagram Code: [go]$$Wc White to play, with no ko ban. Who has the better game, White or Black? $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . O X X . . . | $$ | . . X , . . . . . , . . X X O , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . X . X O . . . . . . . . . O . . . | $$ | . X O X O . . . . . . . . . . . . . . | $$ | . . . O . O X . . , . . . O . O . . . | $$ | . . . . . X . . . X . . . X O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Enjoy!

Edit: I added :b31:

to up the playout count.

Kirby · #2

mhlepore · #3

jlt · #4

Uberdude · #5

It's easy because I recognize the game (my value network is over-fit) :lol:

Bill Spight · #6

Uberdude wrote:

It's easy because I recognize the game (my value network is over-fit) :lol:

Sorry.

You might like my next one, then.

Edit: Err, that's like. Typo.

hyperpape · #7

Uberdude · #8

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%.

Bill Spight · #9

The first game is one of the Master games, GoGoD 2017-01-03a. White was Yang Dingxin, 5p.

Click Here To Show Diagram Code: [go]$$Wc White to play, with no ko ban. Black has the better game. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . O X X . . . | $$ | . . X , . . . . . , . . X X O , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . X . X O . . . . . . . . . O . . . | $$ | . X O X O . . . . . . . . . . . . . . | $$ | . . . O . O X . . , . . . O . O . . . | $$ | . . . . . X . . . X . . . X O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

OC, it is Black who is ahead, and who won the game.

Click Here To Show Diagram Code: [go]$$Wcm10 Big mistake $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . O X X . . . | $$ | . . X , . . . . . , . . . 2 O , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . a . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . W . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Yang's big mistake, says Elf, is :w10:

,

, a play that we humans had thought was good. As an extension it is a little far from the :wc:

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 :w10:

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. :w10:

was not on Elf's radar at all, with 0 playouts. So Elf estimates Black's winrate after :b11:

at 67% with 28.9k playouts.

Click Here To Show Diagram Code: [go]$$Wcm10 Solid connection $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . O X X . . . | $$ | . . X , . . . . . 3 . . . 1 O , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 2 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

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 :w10:

White made a number of small errors.

Click Here To Show Diagram Code: [go]$$Wcm22 8½% loss $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . O X X . . . | $$ | . . X , . . . . . , . a X X O , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 2 . . . . . . . . . . . . . . . | $$ | . . X 1 . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . O . O . . . | $$ | . . . . . X . . . X . . . X O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The largest of these was the jump attachment, :w22:

, instead of the nose attachment at a. The nose attachment has a Black winrate estimate of 68½% with 56.7k playouts. :w22:

was scarcely on Elf's radar, with only 34 playouts. Elf awarded it the Black winrate estimate after :b11:

of 77% with 29.9k playouts. :w22:

lost 8½%.

Click Here To Show Diagram Code: [go]$$Wcm22 The nose attachment $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . 5 7 O X X . . . | $$ | . . X , . . . . . , . 1 X X O , X . . | $$ | . . . . . . . . . . 3 2 . . . . . . . | $$ | . . O . . . . . . . 6 4 . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . W 9 0 8 . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . O . O . . . | $$ | . . . . . X . . . X . . . X O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

=

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.

Click Here To Show Diagram Code: [go]$$Wcm30 Ko, for a loss of 8% $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . O X X . . . | $$ | . . X , . . . . . , . . X X O , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . X . X O . . . . . . . . . O . . . | $$ | . 2 1 X O . . . . . . . . . . . . . . | $$ | . . . O . O X . . , . . . O . O . . . | $$ | . . . . a X . . . X . . . X O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The second largest error, in terms of winrate, was :w30:

instead of the block at a. White a yields a Black winrate estimate of 89½% with 108.8 playouts. :w30:

was on Elf's radar, with 1.5k playouts, but :b31:

has 29k playouts with a Black winrate estimate that rounds to the same figure, 81½%. :w30:

loses 8%.

Click Here To Show Diagram Code: [go]$$Wcm30 The block takes the corner $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . O X X . . . | $$ | . . X , . . . . . , . . X X O , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . X . X O . . . . . . . . . O . . . | $$ | . . . X O 5 4 . . . . . . . . . . . . | $$ | . 7 2 O . O X . . , . . . O . O . . . | $$ | . . 3 . 1 X . . . X . . . X O . . . . | $$ | . . . . . 6 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf's main line after the block.

Bill Spight · **#10**

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?

Click Here To Show Diagram Code: [go]$$Wc Position after White 40. Black to play. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X O . . . . . , . . . . . , . . . | $$ | . . X O X . . . . . . . . . . . X . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X O . . . . . . . X . . . | $$ | . . X , . . O O . X . X . . . , . O . | $$ | . . O O O . X X . . . . . . . X O . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Enjoy!

Uberdude · **#11**

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.

Something I often do when I see a position like this is wonder what the order of play was to reach it. That could also provide a way to judge who is ahead rather than just doing a positional analysis/count, who's made more/bigger mistakes on the way here from the ~even empty board?

Bottom right looks like a far approach to Kobayashi flavour and responding to r3 is one of the urgent points so was likely the last move. Probably k4 was already present to justify choice if back 2 over corner kosumi, but was m4 there already? (if so is it overconcentrated and corner kosumi better?). Also 6 here is weird: usually if you push with 4 you are going for centre so would play 6 high

Click Here To Show Diagram Code: [go]$$Wc $$ . . . . . . . . . . | $$ , . . . . . , . . . | $$ . . . . . . . 6 . . | $$ . . . . . . . . . . | $$ . . . . . . . 5 . . | $$ . . . . . . 4 1 . . | $$ . . . . . . 2 . . . | $$ X . . . . . , . 3 . | $$ . . . . . . X 7 . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------+[/go]

Top shimaris and extension were probably soon after 4 corner moves.

Bottom left is harder to figure out. h4 looks like peep against a one point jump which black resisted by blocking under h3 instead of g4 connect and sacrifice one stone, so that probably happened after white built the big wall and he feared being heavy if connect so k4 and m4 probably not there yet. Corner looks like white attached and extending from either coming into a 5-3 at c5 and g3 pincer, or black approached a white 3-4 and white tenukied. Then some 4th line pushing, but e9 hane on 5th line got cut.

So how about starting something like (5 could be at 7 first, then white 6, black 5; or even black 3 could be at 4, quite a few plausible orders). :w10:

as attach rather than kosumi is unusual,

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 2 . . . . . 8 . . . . . . . . . | $$ | . . . , . . . . . , . . . . 7 , 1 . . | $$ | . . 6 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 5 0 . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . 4 . . 9 . . . . . . . . 3 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Also I feel that playing with many moves to come in a row in lower left with lower right unapproached is odd. And turn at 16 is rather clumsy, fancy moves like g6 attach appeal or just f6 kosumi or make table shape at f3 to stop black's peep there.

Click Here To Show Diagram Code: [go]$$Bcm11 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 9 0 . . . . . . . . . . . . . . | $$ | . . . 7 8 . . . . . . . . . . . . . . | $$ | . . . 1 6 . . . . . . . . . . . . . . | $$ | . . X O 2 . 5 . . . . . . . . . . . . | $$ | . . 3 , . . . . . , . . . . . , . . . | $$ | . . 4 O . . X . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Because peep at 21 now getting answered is unrealistic, white would surely hane at d9. But can black really get it earlier; maybe before 15 jump but then white answering feels a bit slack as black can't really threaten to push and cut with c6 weakness. Black hane at 23 also seems odd if white can cut, why not just extend? So maybe this was the timing for h4 peep. And now I think black would answer that at k4 first, then white push through and then h3, because h3 first white would extend or jump to k4 not push through.

Click Here To Show Diagram Code: [go]$$Bcm21 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . 0 3 . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . X O O . X 8 . . . . . . . . . . . | $$ | . . X , . . 6 4 . 5 . 9 . . . , . . . | $$ | . . O O 2 . X 7 . . . . . . . X . . . | $$ | . . . . . 1 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

So maybe was black was planning to save 23 if white cut before white peeped at 24, but after he's made that strength (in exchange for black develop lower side) decided to switch to 3rd line crawl and sacrifice e9 for now rather than fighting. And that could explain the huge seemingly urgent atari at d11 being unplayed, maybe white feared that if he extended there black would crawl another time or two and then enclose lower right (say at 34) so that's why we have 2 locally urgent shapes.

Click Here To Show Diagram Code: [go]$$Bcm31 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 3 2 . . . . . , . . . . . , . . . | $$ | . . 1 O X . . . . . . . . . . . 9 . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . 8 . . | $$ | . . . X O . . . . . . . . . . 7 4 . . | $$ | . . X O O . X O . . . . . . . 5 . . . | $$ | . . X , . . O O . X . X . . . , . 6 . | $$ | . . O O O . X X . . . . . . . X 0 . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

But if m4 is there and d11 open would black really q5, isn't corner kosumi better now, or d11 atari, w has no too severe followup, r3 attach maybe? Or maybe h5 m4 was exchanged after q5 on the board.

Hmmm, difficult to find an order all the moves make sense and aren't too bad for the presumably high level game this is. So I think i'll just analyse the position. But the difficulty of finding a tewari for the lower left where white doesn't feel a tad clumsy suggests white's efficiency in that area is lower, but that is somewhat balanced with black's q5 choice combo with m4 feeling inefficient too, and r9 weird. k17 side extension being earlier than bots like is minor minus compared to the fighting at bottom.

If black doesn't prevent it white q2 is huge, both settling the white corner that black was trying to attack with r9 low and destroying black's lower side. So there are 2 normal choices here, descend and hane.

If hane and white blocks then black can atari in sente and get the other urgent move at d11 now that white q2 is gote and black can keep the territory there.

Click Here To Show Diagram Code: [go]$$Bcm41 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 5 . . . . . . . . . . . . . . . | $$ | . . X O . . . . . , . . . . . , . . . | $$ | . . X O X . . . . . . . . . . . X . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X O . . . . . . . X . . . | $$ | . . X , . . O O . X . X . . . , 3 O . | $$ | . . O O O . X X . . . . . . . X O 4 . | $$ | . . . . . X . . . . . . . . . . 1 2 . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

But white 42 is often considered slack: the theory in these far approach Kobayashi joseki is white has already gained with the r3 r2 exchange compared to black attacking with the slow-looking but powerful r3 himself.

So seeing as black got one of the urgent moves white gets the other. So black pushes once (and maybe another, not sure) so the white turn there isn't annoying with the b7 etc shape weakness inside and then either plays in the corner to force the white group to run, or covers in sente at p7/q7 and forces white to live. Given white's centre thickness I think black has little value from p7 so would force white to run and in the process develop the upper right side.

Click Here To Show Diagram Code: [go]$$Bcm41 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 4 . . . . . . . . . . . . . . . | $$ | . . 3 2 . . . . . . . . . . . . . . . | $$ | . . X O . . . . . , . . . . . , . . . | $$ | . . X O X . . . . . . . . . 7 . X . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . 6 O . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X O . . . . . . . X . . . | $$ | . . X , . . O O . X . X . . . , . O . | $$ | . . O O O . X X . . . . . . . X O . . | $$ | . . . . . X . . . . . . . . . . 1 5 . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

I don't think black likes this trade. If black completes the capture with 3 then white 4 feels leike opening tedomari, so maybe he plays m17 himself, but then white can save the 2 stones soon or now.

Click Here To Show Diagram Code: [go]$$Bcm41 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . 4 . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 1 . . . . . . . . . . . . . . . | $$ | . . X O . . . . . , . . . . . , . . . | $$ | . . X O X 3 . . . . . . . . . . X . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X O . . . . . . . X . . . | $$ | . . X , . . O O . X . X . . . , . O . | $$ | . . O O O . X X . . . . . . . X O . . | $$ | . . . . . X . . . . . . . . . 2 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Also something to check is if black gets d11 atari in sente, is the c11 cut working? Ie is it big gain in sente, or leaves a problem:

Click Here To Show Diagram Code: [go]$$Wcm44 53 connects at 48 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . 4 2 . . . . . . . . . . . . . . . . | $$ | . 3 1 X . . . . . . . . . . . . . . . | $$ | . 9 X O O . . . . , . . . . . , . . . | $$ | . 7 X O X . . . . . . . . . . . X . . | $$ | . 6 5 X O . . . . . . . . . . . . . . | $$ | . . 8 X O . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X O . . . . . . . X . . . | $$ | . . X , . . O O . X . X . . . , . O . | $$ | . . O O O . X X . . . . . . . X O . . | $$ | . . . . . X . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Even though white has the g11 ladder to aim at in miai building I don't see a way for white to keep the b12 stones down to 2 liberties without ignoring black's g10 atari to prevent the ladder in sente, and giving up those stones is too big loss. So the aji is bad and a nearby stone could change things, but basically the cut isn't working yet.

Click Here To Show Diagram Code: [go]$$Wcm54 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . 6 5 . . . . . . . . . . . . . . . . | $$ | . X X 1 . . . . . . . . . . . . . . . | $$ | . O O X 2 4 . . . . . . . . . . . . . | $$ | . O X O O 3 . . . , . . . . . , . . . | $$ | . O X O X . . . . . . . . . . . X . . | $$ | . X X X O . . . . . . . . . . . . . . | $$ | . . X X O . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X O . . . . . . . X . . . | $$ | . . X , . . O O . X . X . . . , . O . | $$ | . . O O O . X X . . . . . . . X O . . | $$ | . . . . . X . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Maybe for counting we could assume each player gets a honte, though black's move feels more useful that white's (e.g. corner shenanigans in future):

Click Here To Show Diagram Code: [go]$$Bcm41 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . B . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . X O O . . . . , . . . . . , . . . | $$ | . . X O . W . . . . . . . . . . X . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X O . . . . . . . X . . . | $$ | . . X , . . O O . X . X . . . , . O . | $$ | . . O O O . X X . . . . . . . X O . . | $$ | . . . . . X . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

If black plays 41 as descend it's even easier for white to tenuki (block corner and come out miai) so then white can get d11.

Bki · **#12**

Kirby · **#13**

Bill Spight · **#14**

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 :w40:

Black has an estimated winrate of 91½% (26.3k playouts). However, it was White, Go Seigen, who won by resignation.

BTW, as Uberdude suggested, :wc:

was an approach to the bottom right corner, resulting in a Kobayashi style joseki there.

Click Here To Show Diagram Code: [go]$$Wc Go Seigen (W) vs. Mitsuhara Itaro $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . O . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X O . . . . . , . . . . . , . . . | $$ | . . X O X . . . . . . . . . . . X . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . W . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X O . . . . . . . X . . . | $$ | . . X , . . O O . X . X . . . , . O . | $$ | . . O O O . X X . . . . . . . X O . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

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.

Click Here To Show Diagram Code: [go]$$Wcm24 White 24 combines attack and extension, a 13% error $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . 1 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X . . . . . . . . X . . . | $$ | . . X , . . . . . , . . . . . , . O . | $$ | . . O O O . X . . . . . . . . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

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?

Click Here To Show Diagram Code: [go]$$Wcm24 Invade Black's sphere of influence $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . 2 . . . . . . . . . . . . . . . | $$ | . . . . 4 6 . . . . . . . . . . . . . | $$ | . . . X 3 . 5 . . . . . . . . . O . . | $$ | . . . X O . 7 . . . . . . . . X O . . | $$ | . . X O O . X 8 . 0 . . . . . X . . . | $$ | . . X , . . . . . , 9 . . . . , . O . | $$ | . . O O O . X . 1 . . . . W . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

=

Elf recommends the invasion with :w24:

. This diagram shows Elf's main line. :b25:

secures Black's group. Then :w26:

-

is a flow of the stones resulting in White taking territory on the bottom side.

Click Here To Show Diagram Code: [go]$$Wcm32 A 22% loss $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O 6 . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 4 . . . . . . . . . . . . . . . | $$ | . . X O 5 . . . . , . . . . . , . . . | $$ | . . X O X . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X . . . . . . . . X . . . | $$ | . . X , . . 3 1 . a . . . . . , . O . | $$ | . . O O O . B . . 2 . . . . . X . . . | $$ | . . . . . B . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

may be an error, even in a no komi game. In the game Black played :b33:

at a, but Elf recommends the play on the 3d line, which makes a base with the :bc:

stones and forms a moyo with Black's wall to the right. After :w34:

pushes through the gap, Black plays :b35:

with sente and then switches to the 3d line attachment against the top left corner.

Click Here To Show Diagram Code: [go]$$Wcm32 Double sente $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . X , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 2 1 . . . . . . . . . . . . . . . | $$ | . . X O . . . . . , . . . . . , . . . | $$ | . . X O X . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . . X O . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . X O . . | $$ | . . X O O . X . 8 4 9 . . . . X . . . | $$ | . . X , . . . . 6 7 5 . . . . , . O . | $$ | . . O O O . X . 3 . . . . . . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The main reason I think that :w32:

in the game may have been a mistake at no komi go, as well, is that Elf treats :w32:

in its mainline as a double sente (209k playouts). In which case White should have played it right away. :b35:

is an interesting attack. A pincer, resulting in a run-run to the center, would be bad for Black, given White's strong wall. :w40:

pushes the fight into the center. Simply taking territory would not be good enough.

Knotwilg · **#15**

Now I will peek at the other comments

Bill Spight · **#16**

Game 3.

As always, area scoring with 7½ pt. komi.

Elf estimates a winrate of 92.7% (31k playouts) after :w30:

. Which player is it?

Click Here To Show Diagram Code: [go]$$Wcm30 Black to play. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X X O O . . . | $$ | . . X . . O . . . . . X O O X . O . . | $$ | . X . O . . . . . , . . O X . X . . . | $$ | . X O . . . . . . . . . . . . . . O . | $$ | . X X O . . . . . . . . . . . X . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Enjoy!

Knotwilg · **#17**

Since the ladder works for White, Black should probably use a squeezing tactic like this:

Click Here To Show Diagram Code: [go]$$B Squeeze $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X X O O . . . | $$ | . . X . . O . . . . . X O O X . O . . | $$ | . X . O . . . . . , . 7 O X 0 X . . . | $$ | . X O . . . . . . . . 1 2 4 6 . . O . | $$ | . X X O . . . . . . . a 3 5 8 X . . . | $$ | . . . O . . . . . . . . . . 9 . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

White can probably keep things a little easier like this:

Click Here To Show Diagram Code: [go]$$B Squeeze $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X X O O . . . | $$ | . . X . . O . 9 . . . X O O X 6 O . . | $$ | . X . O . . . . . , . 5 O X 4 X . . . | $$ | . X O . . . . . . . . 1 3 2 . 8 . O . | $$ | . X X O . . . . . . . . . 7 . X . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Can Black play :b7:

and force

?
Truth is: I don't know.

Perhaps White needs to play the ko:

Click Here To Show Diagram Code: [go]$$B Squeeze $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X X O O . . . | $$ | . . X . . O . . . . . X O O X . O . . | $$ | . X . O . . . . . , 3 2 O X 0 X . . . | $$ | . X O . . . . . . . . 1 4 6 7 . . O . | $$ | . X X O . . . . . . . a 5 8 . X . . . | $$ | . . . O . . . . . . . . . 9 . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . b . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

This is difficult to judge. If Black connects at A, White ends the ko and Black still has defects. If Black plays a ko threat at B, then White destroys Black at the top with a double atari at A.

Overall I'm inclined to say White, but I can't find a graceful variation.

Bki · **#18**

Bill Spight · **#19**

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.

Click Here To Show Diagram Code: [go]$$Wcm30 Go Seigen (W) - Sakata, no komi $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X X O O . . . | $$ | . . X . . O . . . . . X O O X . O . . | $$ | . X . O . . . . . , . . O X . X . . . | $$ | . X O . . . . . . . . . . . . . . O . | $$ | . X X O . . . . . . . . . . . X . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

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 :b19:

, which may have also been a mistake with no komi.

Click Here To Show Diagram Code: [go]$$Bcm19 Failure to sacrifice? Loss of 20% $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . X . . O . . . . . . . O . . . . . | $$ | . X . O . . . . . , . . . . . X . . . | $$ | . X O . . . . . . . . . . . . . . . . | $$ | . 1 X O . . . . . . . . . . . X . . . | $$ | . . . 2 . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

caught me by surprise. When I was learning go the sacrificial hane at 20 was joseki. It appears that :b19:

allowed White to make too much outside strength with :w20:

.

Click Here To Show Diagram Code: [go]$$Bcm19 Sacrifice. Main line. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . X . . O . . . . . . . O . . . . . | $$ | . X . O . . . . . , . . . . . X . . . | $$ | . X O . . . . . . . . . . . . . . . . | $$ | . 3 X O 4 . . . . . . . . . . X . . . | $$ | . . 2 1 . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . B . . . | $$ | . . . . . X . . . B . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The ladder works now, but Black has many ladder breakers near the :bc:

stones.

Click Here To Show Diagram Code: [go]$$Bcm23 Main line, continued $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . X . . O . . . . . . . O . . 8 . . | $$ | . X . O . . . . . , . 7 . . . X 9 . . | $$ | . X O . . . . . . . . . 5 . . . . . . | $$ | . X X O O . . . . . . . . . . X . . . | $$ | . . O X . . . . . . . . . 0 . . . . . | $$ | . . O . . . . . . . . . . . 4 . 2 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . 6 a , 3 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . 1 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

At the time, 25 was usual, but today's bots have devalued the sides.

:w28:

is good shape. a would allow a double peep.

Click Here To Show Diagram Code: [go]$$Bcm29 Failure to sacrifice, loss of 12½% $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . 1 X O O . . . | $$ | . . X . . O . . . . . X O O X . O . . | $$ | . X . O . . . . . , . . 2 X . X . . . | $$ | . X O . . . . . . . . . . . . . . O . | $$ | . X X O . . . . . . . . . . . X . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

According to Elf, :b29:

loses 12½%. OC, the subsequent fight is complicated, and there is no komi, so :b29:

was not necessarily a mistake.

Click Here To Show Diagram Code: [go]$$Bcm29 Sacrifice variation $$ --------------------------------------- $$ | . . . . . . . . . . . . . 4 . . . . . | $$ | . . . . . . . . . . . 3 2 X O O . . . | $$ | . . X . . O . . . . . X O O X . O . . | $$ | . X . O . . . . . , . . 1 X . X . . . | $$ | . X O . . . . . . 5 . . . . . . . O . | $$ | . X X O . . . . . . . . . . . X . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

This sacrifice lowers White's winrate estimate to 80%.

Click Here To Show Diagram Code: [go]$$Bcm31 Elf's continuation, I $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X X O O . . . | $$ | . . X . . O . . . . . X O O X . O . . | $$ | . X . O . . . . . , . 1 O X . X 7 . . | $$ | . X O . . . . . . . 5 4 2 . . . . O . | $$ | . X X O . . . . . . . 3 6 . . X . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Wcm38 Elf's continuation, II $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X X O O . . . | $$ | . . X . . O . . . . 4 X O O X . O 2 . | $$ | . X . O . . . . . . 3 X O X . X X . . | $$ | . X O . . . . . . 5 X O O . . . . O . | $$ | . X X O . . . . . . 1 X O . . X . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

White sacrifices the corner for central strength.

Click Here To Show Diagram Code: [go]$$Bcm31 Knotwilg's idea $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . b X X O O . . . | $$ | . . X . . O . . . . . X O O X a O . . | $$ | . X . O . . . . . , 5 4 O X 6 X 3 . . | $$ | . X O . . . . . . . . 1 . 2 . . . O . | $$ | . X X O . . . . . . . . . . . X . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf considers Knotwilg's idea for :b31:

and gives the above variation, with :b33:

pushing into the corner. Next if Black a, White b, I reckon.

The remaining diagrams show the continuation in the actual game.

Click Here To Show Diagram Code: [go]$$Bcm31 Actual game continuation $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X X O O . . . | $$ | . . X . . O . . . . . X O O X . O . . | $$ | . X . O . . . . . , 3 . O X . X . . . | $$ | . X O . . . . . . . . . 2 1 . . 9 O . | $$ | . X X O . . . . . 7 5 . 4 . . X . 0 . | $$ | . . . O . . . . . . 6 . . . . . . . . | $$ | . . O . . . . . . . . . . . . 8 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The fight continues into the center. :w38:

severely attacks Black's small group in the top right.

Click Here To Show Diagram Code: [go]$$Bcm41 Small life, but with sente $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X X O O . 4 . | $$ | . . X . . O . . . 6 . X O O X 3 O . . | $$ | . X . O . . . . . 0 X . O X . X 1 2 . | $$ | . X O . . . . . . . . . O X 5 . X O . | $$ | . X X O . . . . . X X . O . . X . O . | $$ | . . . O . . . . . . O 7 8 . . . . . . | $$ | . . O . . . . . . . . 9 . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Since Black lives with sente, he manages to put some pressure on White.

Click Here To Show Diagram Code: [go]$$Bcm51 White starts to develop the right side $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X X O O . O . | $$ | . . X . . O . 9 . O . X O O X X O . . | $$ | . X . O . . . . 0 O X . O X . X X O . | $$ | . X O . . . . . . 1 . . O X X . X O . | $$ | . X X O . . . . . X X . O . . X . O . | $$ | . . . O . . . . . . O X O . . . . . . | $$ | . . O . . . . . . . . X 2 . . O . . . | $$ | . . . . . . . . . . . 3 . . . . . . . | $$ | . . . , . . . . . , . 7 6 4 . , . . . | $$ | . . . . . . . . . . . 8 5 . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

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.)

Bill Spight · **#20**

Game 4.

As always, assume area scoring with a 7½ pt. komi. After :w30:

Elf gives one player an estimated 88% winrate with 144.2k playouts. Which player is it?

Click Here To Show Diagram Code: [go]$$Wc Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . O . . . . . X . . . . . X O . . | $$ | . . . , . . . . . , . . . . . X O . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . O . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . X X O . . . . X . . . | $$ | . . . , . . . . X O O . . . . , . . . | $$ | . . . O . . . . O X X O O . . X . . . | $$ | . . . . . . . . O . . X X . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Enjoy!

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