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How to answer the unsupported 4-2 submarine invasion?
https://lifein19x19.com/viewtopic.php?f=15&t=15997
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Author:  Gomoto [ Fri Aug 24, 2018 3:15 am ]
Post subject:  How to answer the unsupported 4-2 submarine invasion?

How to answer the unsupported 4-2 submarine invasion?

Consider the large keima.


Attachment:
submarine.jpg
submarine.jpg [ 156.39 KiB | Viewed 1436 times ]


possible continuation:

Attachment:
submarine2.jpg
submarine2.jpg [ 161.03 KiB | Viewed 1436 times ]

Author:  Uberdude [ Fri Aug 24, 2018 3:27 am ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

Black's submarine seems kind of early to me, and the direction of white's shimari is odd too. The idea of playing from the outside with small knight move when your opponent plays 2-4 in inappropriate situations is something I was aware of before bots, but you probably don't see it so much in pro games (most common probably bump to keep corner) because they don't play the 2-4 in inappropriate situations so much (though probably more than we thought). What about if the submarine is played in more typical positions it is used? Also see similar idea from AG http://www.alphago-games.com/view/event ... 12/move/34.

Author:  Uberdude [ Fri Aug 24, 2018 4:54 am ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

Here's a pro game (black Ke Jie vs Zho Ruiyang) with a more typical usage. http://ps.waltheri.net/database/game/74620/. It's from 2016 and has the AlphaGo vs Lee Sedol game 5 opening which was popular back then but now seems so old fashioned! (small shimari, no 3-3 invasions). Black has the distant stone on the left side to support the submarine. Zhou played the classic bump to keep the corner, LZ #157 doesn't think it's so bad, just -1%, but on this position likes to take the outside with the small knight move. LZ thiks the submarine was the worst move of the game so far at -3.6% and preferred knight approach or a move on the top side.
Attachment:
ke jie submarine.PNG
ke jie submarine.PNG [ 698.35 KiB | Viewed 1403 times ]

Author:  RobertJasiek [ Sat Aug 25, 2018 12:34 pm ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

Today, I applied the OP move to win a qualification tournament, thanks! :)

Author:  Gomoto [ Tue Sep 11, 2018 6:45 am ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

Sometimes white will try this (suboptimal) move:

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

Author:  Gomoto [ Tue Sep 11, 2018 6:49 am ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

Possible continuations:

good for black:
Click Here To Show Diagram Code
[go]$$B
$$ ----------------------+
$$ . . . . . . . . . . . |
$$ . . . . . . . O . . . |
$$ . . . . X . 2 . . . . |
$$ . , . . . . O X . . . |
$$ . . . . . 3 1 . . . . |
$$ . . . . . . . . X . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . , . . . . . , . . . |
$$ . . . . . . . . . . . |[/go]

Author:  Gomoto [ Tue Sep 11, 2018 6:54 am ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

also possible (still not good for white):

(after black connects at a, white can play tenuki)

Click Here To Show Diagram Code
[go]$$B
$$ ----------------------+
$$ . . . . . . . . . . . |
$$ . . . . . . . O . 9 . |
$$ . . . . X . 3 . 7 8 . |
$$ . , . . . . O X 2 . . |
$$ . . . . . . 1 5 4 . . |
$$ . . . . . . . a X 6 . |
$$ . . . . . . . . 0 . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . , . . . . . , . . . |
$$ . . . . . . . . . . . |[/go]

Author:  Gomoto [ Tue Sep 11, 2018 6:58 am ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

Sometimes black can consider this:

Click Here To Show Diagram Code
[go]$$B
$$ ----------------------+
$$ . . . . . . . . . . . |
$$ . . . . . . . O 3 . . |
$$ . . a . X . 2 1 . . . |
$$ . , . . . . W X . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . X . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . , . . . . . , . . . |
$$ . . . . . . . . . . . |[/go]

Author:  Gomoto [ Tue Sep 11, 2018 7:04 am ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

Situational:

Blacks plays now at a!

Click Here To Show Diagram Code
[go]$$B
$$ ----------------------+
$$ . . . . . . . . . . . |
$$ . . . . . . 5 O . . . |
$$ . . . . X . 1 2 . 8 . |
$$ . , . . . 4 W X 6 0 . |
$$ . . . . . . 3 7 . 9 . |
$$ . . . . a . . . X . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . , . . . . . , . . . |
$$ . . . . . . . . . . . |[/go]

Author:  Bill Spight [ Tue Sep 11, 2018 8:23 am ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

Gomoto wrote:
Situational:

Blacks plays now at a!

Click Here To Show Diagram Code
[go]$$B
$$ ----------------------+
$$ . . . . . . . . . . . |
$$ . . . . . . 5 O . . . |
$$ . . . . X . 1 2 . 8 . |
$$ . , . . . 4 W X 6 0 . |
$$ . . . . . . 3 7 . 9 . |
$$ . . . . a . . . X . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . , . . . . . , . . . |
$$ . . . . . . . . . . . |[/go]


What situations?

Author:  Gomoto [ Tue Sep 11, 2018 9:23 am ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

@Bill: Sometimes this move is best, but the continuation is heavily depending on the surrounding.

Attachments:
submarinev1.jpg
submarinev1.jpg [ 169.88 KiB | Viewed 1147 times ]

Author:  Gomoto [ Tue Sep 11, 2018 9:33 am ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

possible continuations:

Attachments:
submarinev1b.jpg
submarinev1b.jpg [ 173.18 KiB | Viewed 1145 times ]
submarinev1a.jpg
submarinev1a.jpg [ 171.76 KiB | Viewed 1145 times ]

Author:  Gomoto [ Fri Sep 14, 2018 12:36 pm ]
Post subject:  Re: How to answer the unsupported 4-2 submarine invasion?

2 times application of the move. (Move 46 and 52)

Poor black did not know I had a look at the 4-2 submarine already :twisted:


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