spotting the atari and other issues (Mark's study journal)

Mark356 · **#21**

Thanks, it's good to get another opinion on it.

Mark356 · **#22**

I saw an interesting move in a game that Aguilar played the other day.

The board looks like this. Black had just played the upper-left shimari:

Click Here To Show Diagram Code: [go]$$ Position at move 37 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . X . . . . . | $$ | . . . X . . . . . , . . . . . X . X . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . O , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . X . . . O . . . . | $$ | . . O , X . X . . , . . O O X O O O . | $$ | . . . O O X . . . . X . O X X X X O . | $$ | . . . . . . . . . . . . O O X . . X X | $$ | . . . . . . . . . . . . . . . . X . . | $$ ---------------------------------------[/go]

Where to play next? The left is all low, and both black and white have a toehold, so although there's going to be fighting there, it's not time yet. But on the top, Black has a 9-space gap, and one of the stones is high. So White should be able to either approach the hoshi, or just wedge in there. If White wedges, Black can't prevent White from getting a 2-space extension. So far so good.

However, a 2-space extension really doesn't look all that good for White:

Click Here To Show Diagram Code: [go]$$W Moves 38 to 40 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 4 . . . . . . . . . . . . . . . | $$ | . . . . . 3 . . 1 . 2 . . X . . . . . | $$ | . . . X . . . . . , . . . . . X . X . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . O , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . X . . . O . . . . | $$ | . . O , X . X . . , . . O O X O O O . | $$ | . . . O O X . . . . X . O X X X X O . | $$ | . . . . . . . . . . . . O O X . . X X | $$ | . . . . . . . . . . . . . . . . X . . | $$ ---------------------------------------[/go]

If White played like this, his 2-point jump would be undercut immediately. Black has stones he can run to on either side, so White can't prevent Black from jumping in. White has a presence, yes, but no eyespace.

But that's not what White does. He plays like this:

Click Here To Show Diagram Code: [go]$$W Moves 38 to 40 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . 3 . . . . . . . . . . . . . . | $$ | . . . . . . . . 1 . 2 . . X . . . . . | $$ | . . . X . . . . . , . . . . . X . X . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . O , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . X . . . O . . . . | $$ | . . O , X . X . . , . . O O X O O O . | $$ | . . . O O X . . . . X . O X X X X O . | $$ | . . . . . . . . . . . . O O X . . X X | $$ | . . . . . . . . . . . . . . . . X . . | $$ ---------------------------------------[/go]

He makes a 3-point extension onto the second line! I've seen this 3-point extension before, with the order reversed: the second-line play serving as an approach, and when the opponent defends, to play the 3-point jump. (I may have even seen a 4-point jump from the approach, treating the approach stone lightly. Of course, with the order reversed, you give the opponent the option to hem you in and let you live small in the corner instead.)

This stone looked a bit floppy to me at first: normally you can either split the very large knight's move, or you can live under it. However, the normal sequence doesn't work here, because it's the second line:

Click Here To Show Diagram Code: [go]$$B Moves 38 to 40 $$ --------------------------------------- $$ | . . . . . . 7 . . . . . . . . . . . . | $$ | . . . . O 5 2 3 . . . . . . . . . . . | $$ | . . . . . 6 1 4 O . X . . X . . . . . | $$ | . . . X . . 8 . . , . . . . . X . X . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . O , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . X . . . O . . . . | $$ | . . O , X . X . . , . . O O X O O O . | $$ | . . . O O X . . . . X . O X X X X O . | $$ | . . . . . . . . . . . . O O X . . X X | $$ | . . . . . . . . . . . . . . . . X . . | $$ ---------------------------------------[/go]

And Black would be trapped. So this 3-point jump is not alive yet, but it's at least safe from that.

Of course, this 3-point jump isn't free. Black got 2 types of compensation.

First, the white stones are so low that Black was able to get a lot of thickness above:

Click Here To Show Diagram Code: [go]$$W Moves 40 to 45 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 2 1 5 . . . . . . . . . . . . . | $$ | . . . . 4 3 . . O . X . . X . . . . . | $$ | . . . X . 6 . . . , . . . . . X . X . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . O , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . X . . . O . . . . | $$ | . . O , X . X . . , . . O O X O O O . | $$ | . . . O O X . . . . X . O X X X X O . | $$ | . . . . . . . . . . . . O O X . . X X | $$ | . . . . . . . . . . . . . . . . X . . | $$ ---------------------------------------[/go]

The other compensation that Black got was that although there's definitely space for one eye under there, there's not really room for two. White had to run for life, and eventually connected out to the stones on the right side. If White didn't have stones on the right, perhaps he shouldn't have played this way at all. But there's a big difference between running with no eyes and running with one eye. I'll definitely want to remember this move.

Mark356 · **#23**

I was reading Lessons in the Fundamentals of Go and one thing caught my attention. It's from chapter 5, on spheres of influence, and how territory you have some claim over isn't really yours yet, nor should it always be defended. On page 103:

Click Here To Show Diagram Code: [go]$$c This is a label for the diagram. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . a Q O . . . . . . . . . | $$ | . . . . . . b . X O . . . O O X . . . | $$ | . . . X . X . . X X O O O X . X . . . | $$ | . . . . . . . . . . X X X X . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

This is part of a whole-board exercise: White has just played the marked stone. But the point that got my attention was the sentence: "The most natural thing in the world is for Black to answer at A or B, but if he does not rid himself of this habit of answering, he cannot hope to make progress." He goes on to say that Black should use this point as an opportunity to take control of the game and play somewhere else important, and he'll come out ahead even if he does lose the upper left corner. The right answer in the exercise is where and how Black should invade to make the most of his thickness.

Situations like this come up all the time in my games. My opponent will play a move similar to the marked one, often fairly early, and I'll keep on blocking all the way even though I know it's not time for yose yet. It always pains me to do so, but I always think about the damage my opponent could inflict if I don't answer.

Anyway, I tried ignoring a threat to crawl under in favor of taking an important point elsewhere:

Click Here To Show Diagram Code: [go]$$B Moves 18 to 19 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . X X O . . . . 2 . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O O . . . . . . . . . . . O O 1 . | $$ | . . X . . . . . . . . . . . . . X . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . X . . . . . X . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

(From Zombieboy vs. Shinanami, 3 stones, 3/18.)

I ignored her follow-up as well:

Click Here To Show Diagram Code: [go]$$B Moves 20 to 21 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . X X O . . . . O . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . 2 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 1 a . | $$ | . . O O . . . . . . . . . . . O O X . | $$ | . . X . . . . . . . . . . . . . X . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . X . . . . . X . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

I think her follow-up was a mistake-- if she wanted to follow up, she shouldn't have left the cutting point at "a". Anyway, I'd already expressed my willingness to give up that part of the board in exchange for benefits elsewhere, so I was even happier that I had a chance to cut:

Click Here To Show Diagram Code: [go]$$W Moves 25 to 31 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . X X O . . . . O . . . 2 . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . X . . . . . . . . . . . . . X . . | $$ | . . . X . . . . . . . . . . . O O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . 7 . | $$ | . . . . . . . . . . . . . . . X X 5 . | $$ | . . O O . . . . . . . . . . 1 O O X . | $$ | . . X . . . . . . . . . . . . . X 3 6 | $$ | . . . X . . . . . , . . . . . X . 4 . | $$ | . . . . . . X . . . . . X . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

After this I had only one weak group, my other local stones were connected, and I'd cut off black's stones and was able to get a lot of influence from attacking them later. I did go on to win the game, but I think she could've answered better as well. Maybe just connecting at A as soon as I made the first cut, for instance. I wonder if I'd won the game anyway if Black had successfully undermined my sphere of influence.

Shaddy · **#24**

A small but important detail: in Lessons, black's group is absolutely alive. The only thing white could destroy by the second-line move is territory. In your game, black's move threatens to take your base, and it is quite important to answer.

Mark356 · **#25**

Oh, right! I knew that that hane made me uncomfortable. Quite a big difference, now that you mention it.

Mark356 · **#26**

I was white in this game. Black kicked all my approaches, so I thought this opening went a bit oddly. Anyway, white to play:

Click Here To Show Diagram Code: [go]$$ Position at move 19 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . X , . . . X . , . . . . . , X . . | $$ | . . . . X . . . . . . . . . . O O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O O . . . . . . . . . . . . . . . | $$ | . . X , . . . . . X . . . . . , O . . | $$ | . . . X . X . . . . . . . . O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

I figured that the middlegame should start now, that everything that could expand without conflict had already expanded, and so it was time to invade. I decided to invade the top, because that way, if I got a strong group, I could get a good attack on at least one of Black's top right and top left. So I played right in the middle, like so:

Click Here To Show Diagram Code: [go]$$W Moves 20 to 20 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . X , . . . X . , 1 . . . . , X . . | $$ | . . . . X . . . . . . . . . . O O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O O . . . . . . . . . . . . . . . | $$ | . . X , . . . . . X . . . . . , O . . | $$ | . . . X . X . . . . . . . . O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Of course, Black easily proved that this was a very bad move:

Click Here To Show Diagram Code: [go]$$W Moves 20 to 25 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . X , . . . X . , 1 . 2 . . , X . . | $$ | . . . . X . . . . 4 5 . . . . O O . . | $$ | . . . . . . . . . . 3 . 6 . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O O . . . . . . . . . . . . . . . | $$ | . . X , . . . . . X . . . . . , O . . | $$ | . . . X . X . . . . . . . . O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Now White has a weak floating group in the middle of the board, Black is reasonably strong on both sides, and White cannot easily both make good on the early claim to the top right side and make the weak group strong. Taking care of this group was a big issue for me, and I only made it live and got it out when Black slackened the attack on it later. So invading here was a very bad idea from the start.

I asked Rosi, a 1k who used to be in my ASR class, where White should move instead of invading. Clearly, invading like that is too good for Black. Here is her reply:

Click Here To Show Diagram Code: [go]$$W Position at move 19 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . X , . . . X . , 2 . . . . , X . . | $$ | . . . . X . . . . . . . 1 . . O O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O O . . . . . . . . . . . . . . . | $$ | . . X , . . . . . X . . . . . , O . . | $$ | . . . X . X . . . . . 3 . . O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Her answer is that it's not time to invade yet in this game, that White still has a lot of very easy ways to expand its moyo yet. I hadn't even thought of this White 1!

SoDesuNe · **#27**

I really don't like :w1:

and

. White has two overextended shapes (top left and bottom right), where Black can easily invade or just reduce.
:w1:

just solidies Black it does not even reduce effectivly.
:w3:

takes maybe a bit of territory and might aim at pincering the Black stone. But it's on the fourth line, so a pincer is not even severe. My question is: What does White gain with these moves?

I, too, would have invaded the top side. Maybe at the Hoshi. Black is very loose on the top left side and they surely is a lot of Aji to exploit for White. Though I think White will get trouble with its overextended shape in the top left.

spotting the atari and other issues (Mark's study journal)

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