How a Professional Exploits Aji

[logan]

[hyperpape]

Are there comments on how far Ch'oe read before initiating the sequence? Myself, it took me a minute to convince myself that black had no hope at the end.

[macelee]

This is a very exciting game. Thanks logan to bring this to our attentions. I've found some interesting commentaries from a Chinese site and translated them into English. And I've also prepared a number of diagrams to explain this game:

http://www.go4go.net/go/games/sgfview/5762

[Magicwand]

great game to review.
Thank you.

i haven't count points but usually professionals overplay because it is the only way to play.
i am sure Park knew that his defense had bad aji but i believe the game was too close or black may be down few points.

[SoDesuNe]

i am sure Park knew that his defense had bad aji but i believe the game was too close or black may be down few points.

The review macelee posted states that simply defending on the other side (R2), right at the beginning of the sequence, would have been correct and that White would have "no chance" then.

[Mike Novack]

I rather suspect that not read all the way out (from the start) but similar to the reasoning/decisions in grandmaster chess when a player decides "with a pawn for the exchange and a strong attack there has to be enough somewhere". And this may be similar with regard to that comment, right or wrong, that defending on the other side would have worked. Just as in master chess where the defense is more difficult (more error prone) than the attack precisely because no time to read out all variations.

In other words, go master level intuition "there is enough aji in the situation that a counter attack must win compensation".

Also at play here the tendency for the other master to "accept the challenge". I bet that the analysis which said that the other side works took too much time and the outcome too close to count "over the board".

[Magicwand]

i am sure Park knew that his defense had bad aji but i believe the game was too close or black may be down few points.

The review macelee posted states that simply defending on the other side (R2), right at the beginning of the sequence, would have been correct and that White would have "no chance" then.

I just counted and arrived at conclusion that the game is very close but white ahead.
it is not clear because top white territories are unsettled but i think three black stones are dead with very little aji.

I am only 5D so other player count and let me know if count is different.
I dont understand how anyone can say white has no chance.

[tchan001]

Are there comments on how far Ch'oe read before initiating the sequence? Myself, it took me a minute to convince myself that black had no hope at the end.

If you look at the sgf from weiqi.tom.com for the game, you will notice that at move 79, the game was adjourned for lunch and resumed at 1pm. I would argue that at move 79 the right side was quite well formed and there was plenty of time over lunch for Ch'oe to think about how to play the situation should the play happen as it did.

quote of comment for move 79 from the Chinese sgf

至此中午休息，13：00继续

[Bantari]

I rather suspect that not read all the way out (from the start)

I wouldn't be at all surprised if the sequence was read-out completely from the start. True, its not a short one, but a lot of moves are forced, so its pretty much only a few branches which need to be read out. It seems like it is on a verge of being readable by me wrt. the sequence length, and what I would be unable to do is (a) get the idea to begin with, (b) find out one or two really surprising moves, and (c) evaluate the end position from that far back. I am very far from a pro, so to a pro this should be doable.

Not to mention that without (a) finding the few really surprising moves and then (b) reading it out to the end (i.e. White can kill something or live inside Black's area for sure) - there is no such thing as "there has to be enough somewhere" since White just gave Black a whole bunch of additional points and removed a whole bunch of potentially game-changing aji. In other words, if the sequence did not work for White, it would be a very bad play.

So, I personally believe the sequence was fully read out. Flashy as it is, it does not seem to be too hard for a Go pro.
Regardless what a chess grandmaster might or might not be capable of.

but similar to the reasoning/decisions in grandmaster chess when a player decides "with a pawn for the exchange and a strong attack there has to be enough somewhere". And this may be similar with regard to that comment, right or wrong, that defending on the other side would have worked. Just as in master chess where the defense is more difficult (more error prone) than the attack precisely because no time to read out all variations.

In other words, go master level intuition "there is enough aji in the situation that a counter attack must win compensation".

Also at play here the tendency for the other master to "accept the challenge". I bet that the analysis which said that the other side works took too much time and the outcome too close to count "over the board".

[macelee]

I revisited the original game commentary in Chinese. It is not clear who made those comments, but tom.com almost always invites Chinese professionals to make such commentary, or translates directly from Korean sources. The comment says: "at B105 white suffered major losses and black's advantage is clear". The two moves later: "B107 should simply hane [from the other side], and white does not have any chance". These sound like a very strong opinion that black is leading by a big margin.

[John Fairbairn]

For this portion of the game, the Korean Yearbook commentary says W92 should be 94, and W94 should be 97. B101 and B103 put Black ahead. B107 was the losing move and should be 109.

For the final position it says "I, White, am winning", so presumably the commentary has the authority of Ch'oe himself. The commentary has no reference to !! type moves, which may just be modesty, of course

[logan]

Wow, I'm surprised at the response to this game.

To help answer some questions I put together a few comments done by Mr. Kim In 9-dan of Korea along with the rest of the game.

[jts]

I revisited the original game commentary in Chinese. It is not clear who made those comments, but tom.com almost always invites Chinese professionals to make such commentary, or translates directly from Korean sources. The comment says: "at B105 white suffered major losses and black's advantage is clear". The two moves later: "B107 should simply hane [from the other side], and white does not have any chance". These sound like a very strong opinion that black is leading by a big margin.

In English "W does not have any chance" could mean either "W does not have any chance to win the game" or "W does not have any chance to exploit the aji". Does the idiom in the commentary refer exclusively to the former?

[illluck]

I rather suspect that not read all the way out (from the start)

I wouldn't be at all surprised if the sequence was read-out completely from the start. True, its not a short one, but a lot of moves are forced, so its pretty much only a few branches which need to be read out. It seems like it is on a verge of being readable by me wrt. the sequence length, and what I would be unable to do is (a) get the idea to begin with, (b) find out one or two really surprising moves, and (c) evaluate the end position from that far back. I am very far from a pro, so to a pro this should be doable.

Not to mention that without (a) finding the few really surprising moves and then (b) reading it out to the end (i.e. White can kill something or live inside Black's area for sure) - there is no such thing as "there has to be enough somewhere" since White just gave Black a whole bunch of additional points and removed a whole bunch of potentially game-changing aji. In other words, if the sequence did not work for White, it would be a very bad play.

So, I personally believe the sequence was fully read out. Flashy as it is, it does not seem to be too hard for a Go pro.
Regardless what a chess grandmaster might or might not be capable of.

I agree that the sequence was likely read completely. By comparison, you can look at http://www.lifein19x19.com/forum/viewto ... =12&t=9022 for an example of what a KGS 2-3d (with terrible life and death) might read out given sufficient time. The players in this game are probably 7-9 stones stronger.

[Eerika Norvio]

Thanks for the commented game record, logan. I had a feeling that I almost could understand something (about why white shouldn't atari at J11).