Life In 19x19

I can never remember the format of these tournaments. Shibano won, and Hane lost, but there's a three-player playoff (Hane vs. Kono first, then winner against Shibano) to determine the challenger.

There is a 3-way tie at the top of the Honinbo League. Shibano has a higher rank from previous year so the other two have to play first.

Last time something like this happened was in the 61st Honinbo tournament.

This is the game of Yamashita beating Hane, massive kill!
https://home.yikeweiqi.com/#/live/room/16881/1/13719373

Murakawa Daisuke is one win away from taking the Judan title from Iyama. Game four will be on April 19 locally, and it will be streamed on Nihon Kiin's official Youtube channel.

https://www.youtube.com/channel/UCl4UWk ... ZAhSJAprWQ

For those who didn't get the inference, Murakawa beat Iyama in The 3rd judan game today to take a 2-1 lead. Here's the game in yike. https://home.yikeweiqi.com/#/live/room/17019/1/13966317

Also Shibano missed out on a good chance to challenge for his first title: he tried to make a big Centre vs Kono but it got nibbled away and a few trades later he lost by 1.5. So Kono challenges Iyama for the Honinbo.

Game 4 of the Judan was today. Here is a link to the complete video coverage of the game by the Nihon ki-in: https://www.youtube.com/watch?v=VDWwgXcSQLo.

And here is the game (transcription mine, hopefully without mistakes):



The game was quite nerve wracking and I enjoyed it a lot. It seems to me that Murakawa was often under a lot of pressure but that Iyama never really managed to make him pay for that, having problems of his own (most notably, managing the top right after losing the ko). Some sharp moves by Murakawa at 86, 96 and 116.
I also like the fact that the opening featured two 3-3 points and no hoshi. It's quite refreshing to see something else than the bots openings these days!

And if I am not mistaken, that makes the score 3-1 for Murakawa, which means he is the new Judan!

1st game of the 74th Honinbo, Kono Rin challenging Iyama is underway:

https://home.yikeweiqi.com/#/live/room/18001/1/15184532

Giving the ponnuki to capture the top stones in gote didn't look great to me, and the Yike bot thinks it's awful. At least play the n10 atari, it's not like Iyama to be wimpy. Also looks like he made a small endgame mistake in not playing t10 atari before r7 (makes t7 yose a little bigger). Is that something Cho Chikun would have found? Reminds me of a nice move Cho played (for good endgame anticipating stones which would be captured) that I think explorebaduk posted about but I can't find it now.

Kono started his Honinbo title challenge well, won the 1st game by resignation:



I added just a few variations at the end, from the ones found on the WBaduk server from the pro commentary, showing why Iyama had to resign.

Game 2 is tomorrow, yike broadcast at https://home.yikeweiqi.com/#/live/room/18328/1/15630642.

Update: Kono won again! Is this the end of the Iyama era?

Indeed, it seems surprising for Iyama to have a 0-2 start in a major title!

I added the game record with some variations found on WBaduk.
In particular, I liked a lot the variation for black 147, which results in a spectacular exchange in black's favor.

LeelaZero seems to think that Iyama's losing move is 161 (5 moves before he resigned) - while if I understand correctly, the Japanese commentary seems to say that white was ahead anyway (I wonder if this is because of the 1 point difference in komi between LZ and the game rules).

Hi sorin, at 120, one bot (maybe FineArt) gave 87% for ;
DeepLeela (much lower-powered) gave 60% for .
Very difficult for humans to follow-through like the bots.

sorin wrote: LeelaZero seems to think that Iyama's losing move is 161 (5 moves before he resigned) - while if I understand correctly, the Japanese commentary seems to say that white was ahead anyway (I wonder if this is because of the 1 point difference in komi between LZ and the game rules).

LZ157 seems to disagree with the fact that white was ahead anyway, even if komi is changed to 6.5.
If Black plays at K5, LZ gives White 28% winrate.
If I add a white stone at K12, i.e. I make White play at K12 and Black passes, White's winrate becomes 38%.
I don't know how much worth is a white stone at K12, but certainly at least one point, so apparently LZ157 thinks that, at move 160, Black was leading by more than one point (but the lead wasn't huge, just a few points).

P.S. If, instead of K12, the extra white stone is placed at K13, then White's winrate becomes 49%.

Ed: move 120 is so far away from the end of the game, I had no illusion that one's advantage would hold for 40 moves. I am very surprised by the disagreement about who is winning after move 160 though, between the two camps - humans vs LZ

jlt: I realize my logical fallacy when I said that the disagreement in evaluating the board at move 160 can be due to 6.5 komi (Japanese rule) vs 7.5 komi (LZ), since if black had to give 7.5 komi instead, black would be less likely to win; but even so, LZ favors black. My LZ version is version 220 or so, and it seems in agreement with your 157.

So it looks like Iyama, in agreement with the pro doing the WBaduk commentary, thought that he is behind after white 160 and instead of the safe connection he tried to get extra points by playing risky, and his group died.

sorin wrote:Ed: move 120 is so far away from the end of the game, I had no illusion that one's advantage would hold for 40 moves. I am very surprised by the disagreement about who is winning after move 160 though, between the two camps - humans vs LZ

jlt: I realize my logical fallacy when I said that the disagreement in evaluating the board at move 160 can be due to 6.5 komi (Japanese rule) vs 7.5 komi (LZ), since if black had to give 7.5 komi instead, black would be less likely to win; but even so, LZ favors black. My LZ version is version 220 or so, and it seems in agreement with your 157.

So it looks like Iyama, in agreement with the pro doing the WBaduk commentary, thought that he is behind after white 160 and instead of the safe connection he tried to get extra points by playing risky, and his group died.

We have to remember that winrate estimates are based upon players making mistakes. Otherwise they would be 0% or 100% and go might be less interesting. Furthermore, because of self play training, LZ's winrate estimates are based upon LZ's errors, which may be of a different kind than human errors. (In fact, we know that bots and humans make different kinds of errors. ) So top humans could be right that White is more likely to win the game, based upon human errors, while LZ is also right that Black is more likely to win the game, based upon LZ's errors.

Bill Spight wrote: We have to remember that winrate estimates are based upon players making mistakes. Otherwise they would be 0% or 100% and go might be less interesting. Furthermore, because of self play training, LZ's winrate estimates are based upon LZ's errors, which may be of a different kind than human errors. (In fact, we know that bots and humans make different kinds of errors. ) So top humans could be right that White is more likely to win the game, based upon human errors, while LZ is also right that Black is more likely to win the game, based upon LZ's errors.

Sure, if we are talking fuseki I wouldn't take the relative AI winrate estimates of some moves too literally, but here are are at move 160 and not a lot of open areas remaining, so it's the kind of position where top humans are normally confidently estimating the result within 1-2 points I would say. From what I understand they are confident that white is winning.

LZ is also pretty confidently estimating that black is ahead (70+%).

One of these two groups is wrong. Which one?

It is possible that LZ running on my computer is missing something about the upper-left seki, that is a likely possibility, so I would be curious if others can analyze the position at move 160. Or if some pro is willing to play against LZ from that position...