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 Post subject: Trick move by Shin Jinseo 9p?
Post #1 Posted: Wed Jun 20, 2018 11:03 am 
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Trick move?

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


Info
Kim Sedong, 6p - Shin Jinseo, 9p, B+R (Komi 6.5)
Korean JTBC Cup, 2018-06-18


Last edited by Gomoto on Wed Jun 20, 2018 11:07 am, edited 1 time in total.

This post by Gomoto was liked by: Kirgan
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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #2 Posted: Wed Jun 20, 2018 11:05 am 
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What is your next move white? (The next move is critical.)

I think Kim Sedong got tricked by Shin Jinseo in this position.

Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . O . X . . . X . . . . . , X . . |
$$ | . . . . O X . . . . . . . . 1 X . . . |
$$ | . . . . . . . . . . . . . . 2 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #3 Posted: Thu Jun 21, 2018 5:44 am 
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Solution:

tricked (game variation):

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


much better for white:
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . O O 4 . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . O . X . . . X . . . . . , X . . |
$$ | . . . . O X . . . . . . . 3 1 X . . . |
$$ | . . . . . . . . . . . . . . 2 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #4 Posted: Thu Jun 21, 2018 6:10 am 
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I wonder whether the go pros prepare this kind of trick moves like chess pros?

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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #5 Posted: Thu Jun 21, 2018 9:50 am 
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By definition, professionals don't play "trick moves".
Just because it looks strange, and it may trick you, or me, it doesn't mean it is meant to trick his opponent.

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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #6 Posted: Thu Jun 21, 2018 11:33 am 
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Quote:
By definition, professionals don't play "trick moves".
Just because it looks strange, and it may trick you, or me, it doesn't mean it is meant to trick his opponent.


That doesn't sound right to me. OK, we can get bogged down in what mean by "trick" move (which debate is made murkier by people misunderstanding the difference between hamete and inchiki), but surely all moves we all play are made in the hope the opponent won't answer correctly. Not much point making them otherwise, no?

Inchiki is swindling, which pros in go generally eschew - though it is not unknown; pros in most sports cheat more than amateurs, after all. I suppose what you mean is that a pro won't try a swindle against another pro because it will likely backfire and cause more harm than good. But hamete, which is almost entirely limited to the opening (i.e. has strategic overtones), is not swindling: it is simply laying a trap. It is a characteristic of many (?most) hamete that correct play by the opponent does not necessarily lead to significant harm for the trapper. It's like a trapper in real life. His trap may remain empty but the trapper is unharmed and at worst goes hungry for a while.

Traps of this hamete type are commonly researched and played by pros. Probably all the more so now that so many games are played with Mickey Mouse time limits. It may or may not be relevant that the game referred to here was played at the ridiculous speed of 20 minutes plus 20 seconds byoyomi. This seems to be going against the grain, as there has been some reaction to short time limits. Some time limits are being lengthened and some team events are apparently now using a duplex system of blitz games and at least one slow game per match.

However, in this particular case I'm not at all sure that Sin Chin-seo played a hamete (Black 15) because this move is a rather common thematic move in this sort of position. A little earlier than usual, admittedly, but I would not be surprised if he himself described it as a probe. It does seem possible that Kim Se-tong got his knickers in a twist because his hiki response (White 18) is unusual in this shape (did he misplace it through playing at speed?), but I would have thought that the most usual basis of a trap is that the opponent is expected to make the obvious but wrong move - he made the unexpected one. If this was a real trap, the hunter maybe got a deer instead of the (half-)expected rabbit.

Of course, it may be that Kim knew all along what he was doing and was happy with the result in the lower right (doesn't look too bad to me, at any rate). His eventual loss seems more to do with a possible misread of an almost standard life-and-death shape in the upper right.


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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #7 Posted: Thu Jun 21, 2018 1:46 pm 
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Perhaps you will say he's not a real pro, but Alexander Dinerstein 3p is well known for his love of trick moves. He will often prepare some for a tournament, and he also wrote a book about them with An Younggil.

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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #8 Posted: Thu Jun 21, 2018 5:07 pm 
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Thanks John for your detailed and knowledgeable answer.

Now I got a first glimpse of the meaning of proper hamete versus vulgar trick play. I really enjoyed the trapper analogy.

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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #9 Posted: Thu Jun 21, 2018 5:17 pm 
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To John's message: the definition for "trick move" that I objected to is the one where correct reply from the opponent will result in a loss, so one would make such a move either just for fun (in an unofficial game), or when one thinks that their chances of winning are low (the opponent is much stronger, so the chances of playing normally and win are lower than the chances that the opponent will not know the correct answer to the trick move, and get tricked).

Of course, if the game is bad and one is losing anyway, pros may try one last chance with some tricky-looking move, but that is outside of the above definition (since the game is already lost).

To Uberdude's message: I am aware of Alex Dinerstein's trick moves study; I don't think he would play any move that would lower his perceived chances to win the game though. I assume he may try some new trick move against top pros maybe, but not against someone at his own level - just my guess, I don't have any record of when/if he actually plays the trick moves he researched.

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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #10 Posted: Fri Jun 22, 2018 2:37 am 
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To bring this back to technical discussion, P4 is clearly a dubious move that LZ even did not consider. By playing P4 white lost about 5% of winning rate, although the significance of that cannot be quantified easily.


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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #11 Posted: Fri Jun 22, 2018 2:46 am 
Judan

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p4 did seem a pretty clumsy shape, it's like white played p4 first (kinda slow but not totally stupid), black played o2 knight's move which is sensible (block also possible, is it better/worse?), and then white played crude p3 push with p2 block answer bad exchange. But white then played s5 hane and black answered at s4 so white managed to sort of cut off s8 in sente. So my thinking is s5 was sente thanks to p4, because if black ignores white has the r3 tesuji. Maybe that was Kim's plan and reason for p4?

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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #12 Posted: Fri Jun 22, 2018 3:18 am 
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Uberdude wrote:
p4 did seem a pretty clumsy shape, it's like white played p4 first (kinda slow but not totally stupid), black played o2 knight's move which is sensible (block also possible, is it better/worse?), and then white played crude p3 push with p2 block answer bad exchange. But white then played s5 hane and black answered at s4 so white managed to sort of cut off s8 in sente. So my thinking is s5 was sente thanks to p4, because if black ignores white has the r3 tesuji. Maybe that was Kim's plan and reason for p4?


This analysis is wonderful! Pros normally won't play a clumsy move without some sensible idea, even under time pressure as suggested by others in this thread.

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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #13 Posted: Fri Jun 22, 2018 3:45 am 
Honinbo

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macelee wrote:
To bring this back to technical discussion, P4 is clearly a dubious move that LZ even did not consider. By playing P4 white lost about 5% of winning rate, although the significance of that cannot be quantified easily.


Just to show how bots have influenced my thinking, O2 was my first thought, Q4 was my second. ;)

But for analysis I would want at least 10K rollouts for each main option (all four in this case)

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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #14 Posted: Fri Jun 22, 2018 4:39 am 
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Bill Spight wrote:
But for analysis I would want at least 10K rollouts for each main option (all four in this case)


I was using my laptop which is not powerful enough to obtain 10k within reasonable amount of time. But even if we have 10k, I doubt it would pick up other locations like P4.

BTW, to use LZ, we seriously need to get a proper GPU. Last weekend, my son asked me to show him the inside of a computer after reading a computing book. I found a 12 year old computer in my garage and it actually still booted without problem. It has an old NVidia card, a card about 15 generations older than the current ones. When I compiled Leela Zero on that machine, to my surprise this very old card still managed to generate rollouts 4 times faster than my brand new laptop (using an Intel i7 CPU).


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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #15 Posted: Fri Jun 22, 2018 6:36 am 
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sorin wrote:
To John's message: the definition for "trick move" that I objected to is the one where correct reply from the opponent will result in a loss, so one would make such a move either just for fun (in an unofficial game), or when one thinks that their chances of winning are low (the opponent is much stronger, so the chances of playing normally and win are lower than the chances that the opponent will not know the correct answer to the trick move, and get tricked).

Of course, if the game is bad and one is losing anyway, pros may try one last chance with some tricky-looking move, but that is outside of the above definition (since the game is already lost).

To Uberdude's message: I am aware of Alex Dinerstein's trick moves study; I don't think he would play any move that would lower his perceived chances to win the game though. I assume he may try some new trick move against top pros maybe, but not against someone at his own level - just my guess, I don't have any record of when/if he actually plays the trick moves he researched.


Maybe he is more likely to play on the board moves that are technically 'inchiki', but reduce the odds of winning so minimally against a correctly responding human opponent, as to virtually render it 'hamate' in practical terms.

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 Post subject: Re: Trick move by Shin Jinseo 9p?
Post #16 Posted: Fri Jun 22, 2018 10:05 am 
Honinbo

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macelee wrote:
Bill Spight wrote:
But for analysis I would want at least 10K rollouts for each main option (all four in this case)


I was using my laptop which is not powerful enough to obtain 10k within reasonable amount of time. But even if we have 10k, I doubt it would pick up other locations like P4.


I would want 10K rollouts to have confidence in the difference in win rates. I expect that their accuracy depends in large part on the number of rollouts. √(1/10,000) = 1%, so with 10,000 rollouts for each option I would feel pretty confident that if option A has a win rate 3% better than the win rate for option B, then option B is a mistake, and if the difference is 2% it is probably a mistake. The easy way to do this is not to wait until the number of rollouts gets large enough, but to play each option and run them for 10K rollouts. :)

Quote:
BTW, to use LZ, we seriously need to get a proper GPU. Last weekend, my son asked me to show him the inside of a computer after reading a computing book. I found a 12 year old computer in my garage and it actually still booted without problem. It has an old NVidia card, a card about 15 generations older than the current ones. When I compiled Leela Zero on that machine, to my surprise this very old card still managed to generate rollouts 4 times faster than my brand new laptop (using an Intel i7 CPU).


Back in the 1990s I asked Anders Kierulf why, what with Moore's Law, my new computer was slower than my computer from 10 years before. He just laughed. ;)

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