Sanrensei question

chef · Post by **chef** » Tue Jun 03, 2014 7:54 pm

What are your thoughts about this follow up to white? I ask because I played a game where this happened. I still won but I didn't know if I played it well or if my opponent made a mistake.

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

My this is what I played in the game.

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

I'm really curious about two things. Did white make a mistake or did he know what he was doing? And secondly what is the optimal way of responding to

Abyssinica · Post by **Abyssinica** » Tue Jun 03, 2014 9:21 pm

I can't say much, but I know

is a legitimate invasion of the sanrensei.

chef · Post by **chef** » Tue Jun 03, 2014 9:46 pm

I should clarify that. I know it's a legit move, I'm curious about how white played it out.

Bill Spight · Post by **Bill Spight** » Tue Jun 03, 2014 9:51 pm

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

I don't know if

is a mistake, but

very probably is. Why? Because it allows

, which makes a hane-at-the-head-of-two-stones shape, which is good for Black.

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

While normally pushing from behind is not so good, in this case Black gets to make a wall on the fourth line while White makes third line territory. Note

. It is the standard play in this kind of situation to coordinate with the

stone. Each step by White adds only 2 points of territory in the limit, while each step by Black (this early in the game) adds more than 3 points worth of influence. (DrStraw and I are in close agreement about that.)

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

looks like the right play for White. Then

is simple and strong. Now if

connects at 9, Black has a good play at 5. After

and

, it is not clear where White should play. If White plays as in the diagram, he is a bit overconcentrated.

Edit: DrStraw spelling corrected.

EdLee · Post by **EdLee** » Tue Jun 03, 2014 10:18 pm

To add to Bill's post, if I may: notice the first move

is a hane;
anything other local reply seems soft, to me.

Aidoneus · Post by **Aidoneus** » Wed Jun 04, 2014 3:23 am

Bill Spight wrote:Each step by White adds only 2 points of territory in the limit, while each step by Black (this early in the game) adds more than 3 points worth of influence. (Dr. Straw and I are in close agreement about that.)

This seems quite reasonable and a useful general observation. Does there exist a thread where you and DrStraw have discussed this?

Cassandra · Post by **Cassandra** » Wed Jun 04, 2014 3:27 am

EdLee wrote:To add to Bill's post, if I may: notice the first move is a hane;
anything other local reply seems soft, to me.

I would name

an "osae", just because it blocks from above.

John Fairbairn · Post by **John Fairbairn** » Wed Jun 04, 2014 3:32 am

I can't say much, but I know is a legitimate invasion of the sanrensei.

There is not a single example of this in pro database games, even late in the game.

Abyssinica · Post by **Abyssinica** » Wed Jun 04, 2014 3:42 am

John Fairbairn wrote:
I can't say much, but I know is a legitimate invasion of the sanrensei.
There is not a single example of this in pro database games, even late in the game.

Are you sure? I'm pretty sure a professional developed this move.

Uberdude · Post by **Uberdude** » Wed Jun 04, 2014 3:56 am

It looks strange to me too; not a usual invasion in my experience. What I have seen is it played when white caps the middle hoshi stone and black answers that cap with his own cap, as in a spectacular Cho vs Takemiya game I've posted here before (and that's where white has already taken both corners and black has walls facing the right side). Cho ends up living by losing a corner. Something else I've seen is Shuko advocating the 2nd line invasion under the middle hoshi in later positions arising from the san ren sei.

DrStraw · Post by **DrStraw** » Wed Jun 04, 2014 4:30 am

Aidoneus wrote:
Bill Spight wrote:Each step by White adds only 2 points of territory in the limit, while each step by Black (this early in the game) adds more than 3 points worth of influence. (Dr. Straw and I are in close agreement about that.)
This seems quite reasonable and a useful general observation. Does there exist a thread where you and DrStraw have discussed this?

Thank you for the correct appellation. Bill seems to want to refer to me as Dr. Straw, not DrStraw.

As for your question, I don't recall a specific thread, more just comments scattered throughout the forum.

PeterPeter · Post by **PeterPeter** » Wed Jun 04, 2014 4:42 am

That looks like a good topic for a separate thread.

http://lifein19x19.com/forum/viewtopic.php?f=10&t=10399

ez4u · Post by **ez4u** » Wed Jun 04, 2014 5:04 am

Abyssinica wrote:
John Fairbairn wrote:
I can't say much, but I know is a legitimate invasion of the sanrensei.
There is not a single example of this in pro database games, even late in the game.
Are you sure? I'm pretty sure a professional developed this move.

GoGoD has no examples with san-ren-sei. Nevertheless it can give us some ideas...

Click Here To Show Diagram Code: [go]$$Bc Murase Yakichi (White) - Hattori Hajime 1857-07-01 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . O . O O O . . . . | $$ | . . O , . . . . . , . X X X . , X . . | $$ | . . . O . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . X O . . . | $$ | . . . , . . . . . , . . . O O X X . . | $$ | . . . . . . . . . . . . . . . O X . . | $$ | . . X . . . . . . . . . . . O . X . . | $$ | . . . O O . . . . . . . . . . . . . . | $$ | . . X X O . . 8 . . . . . . . O X . . | $$ | . . X O . . . . . 6 . . . . . . X . . | $$ | . . X , . . . . 5 O . . . . O , . . . | $$ | . . . 0 O . 7 . 3 1 2 . . . . O . . . | $$ | . . . . 9 . . . . . 4 . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Note the marked stone below was played as a ladder (upper side) breaking attachment on top of the White stone so White continued at the top originally, leading to an 'attachment underneath' by transposition.

Click Here To Show Diagram Code: [go]$$Bc Yi Ch'ang-ho (White) - Chang Hao 1998-08-27 $$ --------------------------------------- $$ | . . . . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . . X O . O . . . . | $$ | . O 0 O O O X . . . X O X O O X . . . | $$ | . 9 . , X X X . . , O O X . . , X . . | $$ | . . X . . . . . . . . . . O O . . . . | $$ | . . . . . . . . . . . . . . X X . 5 . | $$ | . . 8 . . . . . . . . . . X . . 3 4 . | $$ | . . . . . . . . . . . . . . O . 2 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 6 , . . . . . , . . . . . , . . . | $$ | . . O B . . . . . . . . . . . . . . . | $$ | . . 1 7 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . X . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The marked stone below is another ladder breaker. Note that all the examples where the player on top (White below) pushes at

are situations where the opponent (e.g. Black below) holds one or both adjacent corners.

Click Here To Show Diagram Code: [go]$$Wc Kitani Minoru (White) - Takagawa Kaku 1948-11-10 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . O . . . . . | $$ | . . . , . . . . . , X . . . . X . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . O X X . . | $$ | . . . , . . . . . , . . . X X O X . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , X . . . . W 3 5 0 . . X . . . | $$ | . . . . . . 9 7 1 X 2 4 . . . . . . . | $$ | . . . . . . . 8 6 . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

daal · Post by **daal** » Wed Jun 04, 2014 5:20 am

John Fairbairn wrote: There is not a single example of this in pro database games, even late in the game.

I found one (move 130):

DrStraw · Post by **DrStraw** » Wed Jun 04, 2014 5:47 am

daal wrote:
John Fairbairn wrote: There is not a single example of this in pro database games, even late in the game.
I found one (move 130):

Hardly qualifies as a sanrensei at that point.

Life In 19x19

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