Life In 19x19

Well, the second round starts tomorrow so here's a little recap.

Last 10 games between these two players (before the 73rd Honinbo) went 9-1 for Iyama, if I counted well.
Yamashita's only win was in the semi-final of the 4th Championship of Tournament Winners last year. Other than that he lost the 42nd Gosei 0-3 in 2017 and the 40th Kisei 0-4 in 2016, so things were not looking too good at the start of the Honinbo.

First round of the 73rd Honinbo
Complete video footage (in many parts) can be found here, https://www.youtube.com/watch?v=Ez1QfWQuI54
The game record (courtesy of Go4go)

I haven't studied it in any kind of depth but seeing the position after 45 or 99 I found really interesting how white still managed to bring the game so close.

Today Iyama did some goban signing and the two players were apparently caught playing casually in the streets, like you do before a title match game! You can see some images of the pre-game ceremonies and all at 日本棋院若手棋士's twitter.

So what do you expect for the next game? Will Yamashita be able to capitalize on his victory or will an irate Iyama win the next four games?

Shenoute wrote:I haven't studied it in any kind of depth but seeing the position after 45 or 99 I found really interesting how white still managed to bring the game so close.

Actually, LZ believe White is ahead (winrate > 60%) from move 55 to 176. It really dislike 176 at N13 (a loss of 20% winrate).

I know that LZ believe the komi is 7.5 instead of 6.5, so the real end of the game evaluations are not reliable, but it shouldn't be a real problem for the middle game.

Tryss wrote:Actually, LZ believe White is ahead (winrate > 60%) from move 55 to 176. It really dislike 176 at N13 (a loss of 20% winrate).

Thanks! The video coverage came with a sidebar showing winning percentage but I didn't pay much attention to it. I wonder what bot they are using for this.

Game 2

Video coverage here.

There was apparently something special for the beginning of the game, with the first few moves being played in a castle-game(?) like setting. See the pictures at 日本棋院若手棋士.

Game record
Iyama (black) took a long thought (around 45 min?) and sealed his move at this point. Consensus seems to be that black needs to take care of his group in the bottom left by adding a move on the left side. I like how Yamashita went for high positions while letting black have a lot of well defined territory. At first I thought that white didn't have much potential but the top can turn very quickly into a sizeable territory, so there's that I guess. Plus, black's bottom right corner remains open somehow.

This games reminds me of the first Yamashita games I looked at, somewhere around 2006 I guess, when he was fighting Hane Naoki for the Kisei for instance. At that time my impression was that he played a lot of these high position games and I liked that. Afterwards he seemed to play in a less distinctive way.

Black d13 pushy pushy would seem a reasonable continuation to take care of the group with profit, but then white could o18 (and assuming black answers this) close the top from the right in sente and then d18 block (or g17 AlphaGo style?!). Would the top then be white territory? If so that's quite a failure for black IMO, whose c18 gote move should be used to attack that white wall or at least make it nervous, not naturally find safety by making a 40 point territory. r4 and such like does look fun in the future. I wonder if Iyama will find a way to make j6 group worry (j8 one obvious shape attack), it looks pretty safe to me (and g2 emergency sort-of-connection).

Uberdude wrote:Black d13 pushy pushy would seem a reasonable continuation to take care of the group with profit, but then white could o18 (and assuming black answers this) close the top from the right in sente and then d18 block (or g17 AlphaGo style?!). Would the top then be white territory? If so that's quite a failure for black IMO, whose c18 gote move should be used to attack that white wall or at least make it nervous, not naturally find safety by making a 40 point territory. r4 and such like does look fun in the future. I wonder if Iyama will find a way to make j6 group worry (j8 one obvious shape attack), it looks pretty safe to me (and g2 emergency sort-of-connection).

Yes, d13 is a good candidate. Other things I've seen mentioned on Wbaduk were jumping around f10.
After d13, if white plays o18 I would be very tempted not to answer and use sente to reduce the top (e18? f13?) but it is true that white turning at p18 would be sente and weakens b's corner...If white can end in sente maybe simply answering d13 with e13 is satisfying enough? Or maybe that would settle the position too quickly there and remove any possibility to harass black's bottom left group?

Edit. Corrected "d18" to "o18".

So I asked Leela Zero #139, she likes d13 with 54% on 3k playouts and seems pretty single-minded (f9 a distant #2). Doesn't seem a fan of o18 tesuji just playing patzer's atari, but likes s5 as invasion point later.

f10 it was. After o18, kosumi yamashita's 3-3 was sharp, I suppose that's another reason black o18 is honte in this sort of shape.

Yes, that was a nice 3-3!
I have some trouble understanding/evaluating the sequence after f10 on a global level. Something like: "white exchanged (much of) his potential at the top for sente moves in the upper right corner and some reinforcement moves for his center group (K9-L10) while the center black group is still somewhat unsettled"?

A disappointing end...Not that I root for Yamashita at the expense of Iyama but I would have liked to see white use his position to the fullest.
My two cents (for what it's worth): after 105 I thought white might take the outside to strenghten his overall position and reduce b's bottom right corner but Yamashita chose to live in the corner. Probably, it would have been too big to let black take it. Still, I liked white 110, thinking it may lead to an interesting fight in which black center group may suffer but Iyama skillfully managed to take care of his weaknesses (if there were any to begin with!) and used his sente to land a devastating blow at 143 (was 142 too solid at this point?).
Also, white 156-158? "Looking for a place to resign"?

Shenoute wrote: Also, white 156-158? "Looking for a place to resign"?

156-158 are getting the good endgame on that corner before living (other ways of living might mean you have to ignore Black's descent which opens up the corner) though meant he had to sacrifice the 5 stones. Or did you mean 166-168? 166 is ok but 168 is a kyu level blunder to miss the atari or some spectacular harakiri seeing as he was losing anyway (bamboo and white lives with miai for second eye in centre or side, remember a9 is sente). Maybe he wanted to live by saving the o15 cutting stones as that has eyeshape implications on Black's centre group but it didn't work.

Ah, my bad! I missed white's life after 156-158 so I thought these moves only helped to bury the white group.

A few comments based on LeelaZero (#139 <10k playouts) analysis:

Click Here To Show Diagram Code

[go]$$Bcm71 Iyama (black) vs Yamashita
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . X O X . . . . |
$$ | . . X O . . . 6 . , . O O X X X . . . |
$$ | . . X O . . . . . . . . . O . . . . . |
$$ | . X O O . 4 . 5 . . . . . . X O . . . |
$$ | . X X X X O . . . . . . O . . O . . . |
$$ | . O O O . . O 3 . . . . . . . . . . . |
$$ | . . . X O O X X . . . . . . . . . . . |
$$ | . . . O X X . . . , . . . . . , . . . |
$$ | . . . O . . . 1 . . . . . . . . . . . |
$$ | . . . . . X O . 2 . . . . . . . . . . |
$$ | . . X X X X O . . . . . . . . X . . . |
$$ | . . O O . . X O O . . . O . . . . . . |
$$ | . . . . . X . X . . . . . . . . . . . |
$$ | . . . O . X X O O , . . O X . X . . . |
$$ | . . . . O X . . . . . . . X . . . . . |
$$ | . . . . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

When Iyama defended the cut with 71 LZ preferred to hane at 74 by 6%, sees this as the vital point (B still 75% though). Yamashita defended with the good shape move of 72, which keeps up some pressure on black's centre group, but LZ wants to allow that shape attack and play f14 vital point again, with 74 either on lower side to make eyespace or s5 invasion. And again it wants black to play f14 instead of 73 (or with e12 first), -9%. Agrees with white's f14 (miai with h12) and black jump, but then would prefer to attach at h15 instead of h16. We did see the g15 weakness being a problem in the game and white did actually end up playing at h15 as well later. I suppose white didn't want to attach because it also strengthens black in the centre, but leaving the g15 hole means white is weaker too so perhaps in terms of relative strength black is no worse off.

Click Here To Show Diagram Code

[go]$$Bcm71 variation for 72.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . X O X . . . . |
$$ | . . X O . . . . . , . O O X X X . . . |
$$ | . . X O . . . . . . . . . O . . . . . |
$$ | . X O O . 2 . . . . . . . . X O . . . |
$$ | . X X X X O . . . . . . O . . O . . . |
$$ | . O O O . . O . . . . . . . . . . . . |
$$ | . . . X O O X X . . . . . . . . . . . |
$$ | . . . O X X . . . , . . . . . , . . . |
$$ | . . . O . . . 1 . . . . . . . . . . . |
$$ | . . . . . X O . 3 . . . . . . . . . . |
$$ | . . X X X X O . . . . . . . . X . . . |
$$ | . . O O . . X O O . . . O . . . . . . |
$$ | . . . . . X . X . . . . . . . . . . . |
$$ | . . . O . X X O O , . . O X . X . . . |
$$ | . . . . O X . . . . . . 4 X . . . . . |
$$ | . . . . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

P.S an interesting big picture judgement, LZ sees 55 as a black mistake (game pretty even at that point) and should play other block, and white should punish by tenukiing and just playing a big move at s5, which it seems rather obsessed about (we know LZ highly values corners, does it undervalue balance of power of that black group?), but white's continued play there of hane and then clamp sees white's win rate plummet as he chases black's group out but also allows black to poke into white's top and has crummy shape (my interpretation).

Game 3 (first day)

Game 3



The score is now 2-1 for Iyama.
The game is of course far too complex for me to analyze but two moves really surprised me:
- 143, leaving the left side as is in order to not even kill the corner (since white can still live with Q1 even after 143)
- 155, did black dislike so much not having two eyes locally after something like e6- d6- b6- b3 (while on the other hand d6 at least gave him an unconditionally living group on the side)? If so, the cost seems pretty high, with the center stones not having eyes and white stones being much stronger because of the f5 cut.