Opening problem

PeterPeter · #1

Click Here To Show Diagram Code: [go]$$B Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . . O . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . b , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . X X . . . . . . . . . . . . . . . . | $$ | . O X . X . . . . . . . . . e . c . . | $$ | . O O X . . O . . . . . . . . . d . . | $$ | . O X O X X . X . , . . . . . O . . . | $$ | . . . O O . . . . . . . . a . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

In this question about the best move to play next, I did get the correct answer (not shown), but I also had a couple of candidate moves than I am less sure about.

'a' was only rated 6/10, with the commentary being that it "is not appropriate here, because Black's position on the lower left is open at the edge of the board." Can anyone explain this further?

'b' was not rated at all. What is wrong with this cap?

I did not like the look of 'c', which was rated 8/10, after white replies at 'd'. I thought this invasion looked unwise and unnecessary. What if white replied at 'e' instead?

amnal · #2

Quote:

'a' was only rated 6/10, with the commentary being that it "is not appropriate here, because Black's position on the lower left is open at the edge of the board." Can anyone explain this further?

a is not an interesting place to make territory or a moyo because white can undercut it or black has to spend a move there in gote. Meanwhile, white can't make much territory there himself because any large extension can probably be invaded thanks to black's thickness, so the area isn't that interesting to play in

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

For instance, if black plays some simple joseki that he vaguely remembers reading in a book somewhere, white's move 6 is massive and leaves black with very little territory, not much more influence than he already had, and a stronger white corner than before.

Quote:

'b' was not rated at all. What is wrong with this cap?

I think it's probably just a bit lukewarm. It may well be fine, particularly for non-high-dans, but it isn't sufficiently active. It doesn't really threaten anything as white's two stones both have loads of space around them, and white can even just be induced to become strong near the shimari. In return, black needs to claim that the cap helps his centre enough, but it's wide open right now and it may be fairly easy for white to make the cap a bad move by making the moyo too small for it to matter before it even becomes important.

EdLee · #3

Fix the cut?

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

Otherwise...

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

...B ends up with a big dumpling and another weak group?

Click Here To Show Diagram Code: [go]$$Bm11 $$ ----------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . . O . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . X X . O . . . . . . . . . . . . . . | $$ | . O X 1 X O 2 . . . . . . . . . . . . | $$ | . O O X X X O . . . . . . . . . . . . | $$ | . O X O X X O X . , . . . . . O . . . | $$ | . . . O O O X X . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ -----------------------------------------[/go]

As we see in the actual 1969 pro game, when W eventually pushes with :w2:

,
B cannot block with :b3:

(otherwise we result in the above huge dumpling);
instead, B can only turn, resulting in the broken shapes in the real game --
so the fixing the LL peep is not that urgent.

PeterPeter · #4

That was only rated 5/10. Nothing more was said about it. My feeling was that it was useful, but not that urgent. If black wanted to block off that corner, he could do so later?

EdLee · #5

Peter, may I ask which book the problem came from, who's the target audience, and who's the author (his/her level) ?
( Ishigure Ikuro 石榑　郁郎. In 1973 -- when the book was written? -- 7p. Now: 9p. )
Here's the pro game (first 60 moves) -- the problem changed the order of a few moves, which makes a huge difference:
( :b21:

and

already played; :w24:

is a different atari than B4, etc. -- unless the database is wrong,
or, the problem came from another actual pro game with just ever so slightly different moves!

)

PeterPeter · #6

It is "In the Beginning" by Ikuro Ishigure - I think he is 9 dan?

I am looking at the excellent sequence which you later added, and cannot find a way for that to end well for black.

The opening sequence is not given; just the position.

He does allow for lots of different answers, hence the scale of 1 to 10, rather than right/wrong (though he is confident there is always one answer a bit better than the others).

Magicwand · #7

Surprisingly every pros will agree on such problem.
Which means they see what we don't.

Unusedname · #8

What I think of "c"

Click Here To Show Diagram Code: [go]$$B Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . . O . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . a . . | $$ | . . . . . . . . . . . . . . . . b . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , W . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . 5 . . . | $$ | . X X . . . . . . . . . . . . . . . . | $$ | . O X . X . . . . . . . . . . 3 1 . . | $$ | . O O X . . O . . . . . . . . . 2 . . | $$ | . O X O X X . X . , . . . 4 . O . . . | $$ | . . . O O . . . . . . c . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

i suppose something like this.

The white stone is separated
The corner can still be invaded
Black's enclosure is strong so making a base might be considered slow
Something like c might become sente against the coner which would allow black to turn the side into territory

as far as white playing the cap?

Click Here To Show Diagram Code: [go]$$B Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . . O . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . 3 . . . | $$ | . X X . . . . . . . . . . . . . . . . | $$ | . O X . X . . . . . . . . . 2 . 1 . . | $$ | . O O X . . O . . . . . . . . . . . . | $$ | . O X O X X . X . , . . . . . O . . . | $$ | . . . O O . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

the corner is still open
the stone is still separated
and white is building a useless wall that is facing thickness.

amnal · #9

Unusedname wrote:

What I think of "c"

Click Here To Show Diagram Code: [go]$$B Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . . O . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . a . . | $$ | . . . . . . . . . . . . . . . . b . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , W . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . 5 . . . | $$ | . X X . . . . . . . . . . . . . . . . | $$ | . O X . X . . . . . . . . . . 3 1 . . | $$ | . O O X . . O . . . . . . . . . 2 . . | $$ | . O X O X X . X . , . . . 4 . O . . . | $$ | . . . O O . . . . . . c . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

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

I had thought black might have this 5 in mind, aiming to make the white stone on the side weaker and claiming that 1 and 3 are in an okay position because of black's thickness. Plus black a is very annoying for white so white might prefer to play 4 one line lower, but then he can't attack black's stones as powerfully.

Uberdude · **#10**

EdLee wrote:

Here's the pro game (first 60 moves) -- the problem changed the order of a few moves, which makes a huge difference:
( and already played; is a different atari than B4, etc. -- unless the database is wrong,
or, the problem came from another actual pro game with just ever so slightly different moves! )

This is strange. In the book Ishigure says that his white opponent played b17, which was a mistake, rather than f14 which is the key point and would punish black, as in the game Ed posted. And that he himself made a mistake in playing c16 and hoping that his opponent descended to b17 (which he obliging did) rather than jumping immediately to the key point. So either he is misremembering, or there was another very similar pro game that's not in GoGoD.

Magicwand wrote:

Surprisingly every pros will agree on such problem.
Which means they see what we don't.

Ishigure himself says he got it wrong

P.S. c3 vs b4 actually makes quite a difference to the push through at g4.

Bill Spight · **#11**

Congratulations on finding the cap. You are thinking about the whole board. (Sorry, lovelove.

)

Click Here To Show Diagram Code: [go]$$B Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . . O . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . 1 , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . 2 . . . | $$ | . X X . . . . . . . . . . . . . . . . | $$ | . O X . X . . . . . . . . . . . . . . | $$ | . O O X . . O . . . . . . . . . . . . | $$ | . O X O X X . X . , . . . . . O . . . | $$ | . . . O O . . . . . . . . . . . 3 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

There is a proverb that says to play a knight's move to the cap. But in this case, if :w2:

,

and now White is overconcentrated. (If Black jumped into the corner first, White would not respond at :w2:

.)

Click Here To Show Diagram Code: [go]$$B Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . . O . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 2 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . 1 , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . X X . . . . . . . . . . . . . . . . | $$ | . O X . X . . . . . . . . . . . . . . | $$ | . O O X . . O . . . . . . . . . . . . | $$ | . O X O X X . X . , . . . . . O . . . | $$ | . . . O O . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

But White will respond at :w2:

, which is a play White wanted to make, anyway. Now, :b1:

looks ill placed.

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

To justify the existence of :b1:

, Black might try :b3:

, aiming to build a framework. But then :w4:

counters that strategy.

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

is another possibility, aiming at :b7:

. In this variation Black ends up a bit better on the lower right side that if he had played :b3:

right away, while White is better on the top right side. Still, Black looks overconcentrated.

Opening problem

Who is online