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Bot analysis of Sakata's myoshu
https://lifein19x19.com/viewtopic.php?f=15&t=16266
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Author:  Uberdude [ Tue Dec 04, 2018 1:53 am ]
Post subject:  Bot analysis of Sakata's myoshu

Sinan Djepov (Bulgarian 5d) has a new website explorebaduk.com. His latest article has a nice analysis of a famous tesuji from Sakata Eio that latest LZ didn't spot, but agrees is good when played. I recommend you read that first. I then had a look at Elf v1's opinion, as it sometimes finds sharp moves LZ doesn't (but also suffers from blindspots). First, Elf agrees with LZ that Fujisawa's understandable resistance as a hot-blooded human at m3 was bad and he should have just blocked at o2. If he did that then the tesuji actually lost 6% and white would be at 16% (bear in mind Elf assumes 7.5 komi and this game had less so white would be even worse off).

Click Here To Show Diagram Code
[go]$$Wc Sakata's myoshu
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . X . . . . . X O . |
$$ | . . . O . . . . X . . . . X X X O O . |
$$ | . . . , . . . . X O . . . X O O X . . |
$$ | . . O . . . O . O O . . . . X O . . . |
$$ | . . . . . . . . . . X . X . X O O . . |
$$ | . . . . . . . X . X . . . O O X O O . |
$$ | . . . . . . . . . . . O . O X X X O . |
$$ | . . . . . . . . . O . . . . O . X X . |
$$ | . . . , . . . . . , . . . . . , O X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X . X . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . X X O . . . |
$$ | . . . . . . . . . X X . O O . . O . . |
$$ | . . . , . . . . X O . O . . O O X O . |
$$ | . . O . . . . X . O . . X X . X X X . |
$$ | . . . . . . . O . . . . 1 . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


If Fujisawa passively blocked / answered patiently and bided his time Elf expects white to save the group in gote (the point of the tesuji is it, in sente, made black a-d no longer work to create a double cut weakness) and black then plays 6, a key point for the strength of the white and black groups in the centre which reduces the effectiveness of a white peep at p9. It then expects white to either connect directly at o11 or maybe (within 1%) counter peep with p9 o9 o11 p10

Click Here To Show Diagram Code
[go]$$Wc Patient answer, black at 84%
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . X . . . . . X O . |
$$ | . . . O . . . . X . . . . X X X O O . |
$$ | . . . , . . . . X O . . . X O O X . . |
$$ | . . O . . . O . O O . . . . X O . . . |
$$ | . . . . . . . . . . X . X . X O O . . |
$$ | . . . . . . . X . X . . . O O X O O . |
$$ | . . . . . . . . . . . O . O X X X O . |
$$ | . . . . . . . . . O . . . . O . X X . |
$$ | . . . , . . . . . , . . . 6 . , O X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X . X . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . X X O . . . |
$$ | . . . . . . . . . X X . O O . . O . . |
$$ | . . . , . . . 4 X O a O . . O O X O . |
$$ | . . O . . . . X 3 O c b X X . X X X . |
$$ | . . . . . . 5 O . . d . 1 2 . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


So why does Elf think the tesuji isn't good? The answer seems to be the importance of the p9 peep. It wants to play (over 100k playouts) there immediately rather than do the tesuji and then take gote to save the group. If white peeps now it expects black to simply connect (at other times black resists with o9 push on top) and then plays the j3 moves saving the group but with no n2 exchange to patch the cut weakness. It then expects black to push to punish white for leaving this weakness, pops in the cheeky r9 exchange before pulling black and allowing black to go for the double cut weakness.

Click Here To Show Diagram Code
[go]$$Wc Elf says better for white than myoshu (black at 77%)
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . X . . . . . X O . |
$$ | . . . O . . . . X . . . . X X X O O . |
$$ | . . . , . . . . X O . . . X O O X . . |
$$ | . . O . . . O . O O . . . . X O . . . |
$$ | . . . . . . . . . . X . X . X O O . . |
$$ | . . . . . . . X . X . . . O O X O O . |
$$ | . . . . . . . . . . . O . O X X X O . |
$$ | . . . . . . . . . O . . . . O . X X . |
$$ | . . . , . . . . . , . . . . . , O X . |
$$ | . . . . . . . . . . . . . . 1 . 7 8 . |
$$ | . . . . . . . . . . . . . X 2 X . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . X X O . . . |
$$ | . . . . . . . . . X X . O O . . O . . |
$$ | . . . , . . . 4 X O 6 O . . O O X O . |
$$ | . . O . . . . X 3 O 0 9 X X . X X X . |
$$ | . . . . . . 5 O . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Black cuts on the left (if you cut on the right white will capture anyway and you help white make eyes) and takes the 3 stones, whilst white ends up playing at the n2 tesuji point anyway and then lives with the inside group. Again black uses his sente to annoy the shape of the centre white group. So it seems to me Elf is saying because white shouldn't fear but welcome the exchange of losing the 3 stones, it's better to keep n2 in reserve and only play it when necessary (because black is pushing through at l4) because otherwise it's a slightly bad exchange so better left unplayed.

Click Here To Show Diagram Code
[go]$$Wcm11 Elf's better line continuation, black ends at 78%
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . X . . . . . X O . |
$$ | . . . O . . . . X . . . . X X X O O . |
$$ | . . . , . . . . X O . . . X O O X . . |
$$ | . . O . . . O . O O . . . . X O . . . |
$$ | . . . . . . . . . . X . X . X O O . . |
$$ | . . . . . . . X . X . . . O O X O O . |
$$ | . . . . . . . . . . . O . O X X X O . |
$$ | . . . . . . . . . O . . . . O . X X . |
$$ | . . . , . . . . . , . 9 8 . . , O X . |
$$ | . . . . . . . . . . . . . . O . O X . |
$$ | . . . . . . . . . . . . . X X X . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . X X O . . . |
$$ | . . . . . . . . . X X . O O . . O 6 . |
$$ | . . . , . . . X X O X O . . O O X O . |
$$ | . . O . . . . X O O X O X X 5 X X X . |
$$ | . . . . . . O O 4 2 1 . 3 . . 7 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  seigenblues [ Tue Dec 04, 2018 4:40 pm ]
Post subject:  Re: Bot analysis of Sakata's myoshu

thanks for posting this analysis! It's really interesting. Most minigo's also seem to like the peep at 1 as well.

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