Sanrensei question

chef · #1

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 :w1:

Abyssinica · #2

I can't say much, but I know :w1:

is a legitimate invasion of the sanrensei.

chef · #3

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

Bill Spight · #4

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

I don't know if :w1:

is a mistake, but :w3:

very probably is. Why? Because it allows :b4:

, 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 :b10:

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

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 :b4:

is simple and strong. Now if :w5:

connects at 9, Black has a good play at 5. After :w5:

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 · #5

To add to Bill's post, if I may: notice the first move :b2:

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

Aidoneus · #6

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 · #7

EdLee wrote:

To add to Bill's post, if I may: notice the first move :b2:

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

I would name :b2:

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

;-)

John Fairbairn · #8

Quote:

I can't say much, but I know :w1:

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 · #9

John Fairbairn wrote:

Quote:

I can't say much, but I know :w1:

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 · **#10**

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 · **#11**

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 · **#12**

That looks like a good topic for a separate thread.

viewtopic.php?f=10&t=10399

ez4u · **#13**

Abyssinica wrote:

John Fairbairn wrote:

Quote:

I can't say much, but I know :w1:

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 :w3:

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 · **#14**

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 · **#15**

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.

wineandgolover · **#16**

DrStraw wrote:

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.

Well, John did claim "even late in the game."

What a crazy game, how does that end as black +1? Amazing. Thanks, daaldude.

Bill Spight · **#17**

DrStraw wrote:

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.

Sorry, DrStraw.

Spelling corrected in quoted post.

Quote:

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

Loons · **#18**

I'm a bit bemused by our apparent desire to call :w6:

... Strange Midgame Attachment a reasonable move.

Edit: I realise lots of people were expressing this tacitly, but I think we should be explicit here. :w6:

was not good.

oca · **#19**

Bill Spight wrote:

...

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 :b4:

is simple and strong. Now if :w5:

connects at 9, Black has a good play at 5. After :w5:

and

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

Just to be sure... if :b6:

what should white reply ?
I would say "a".. or is there an escape or good move with the help of :w1:

?

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

Bill Spight · **#20**

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

This is my thinking.

Sanrensei question

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