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Question about invasion
http://www.lifein19x19.com/viewtopic.php?f=11&t=7819
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Author:  ikkyu [ Wed Feb 06, 2013 6:42 am ]
Post subject:  Question about invasion

A little background before my question. I’m a relatively new player, playing on and off for a few months now. Almost all the games I’ve played have been as black in handicap games and, as such, me needing to reduce an opponent’s area wasn’t something that came up. So when I was playing as white in an even game with a friend, I saw that I had to do something to reduce her potential territory but wasn’t certain of the best way to do so. I was able to pull off my invasion, but I have the feeling that I wouldn’t have been so successful against a more skilled opponent. In retrospect, I think maybe a simple reduction might have been better than an invasion.

But I was hoping for feedback on my choice of playing the marked white stone.

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

Author:  skydyr [ Wed Feb 06, 2013 7:43 am ]
Post subject:  Re: Question about invasion

It looks playable to me, and should be difficult to kill. If you invade, a more advanced technique in this case would be to probe someplace like B16 first. Another option, if you count that you could be even or ahead afterwards, would be to make a shallower invasion or reduction, but black's move at N15 has a lot of aji you can work with, and could leave his group on the top right looking for eyes too, with your move.

Author:  HermanHiddema [ Wed Feb 06, 2013 8:45 am ]
Post subject:  Re: Question about invasion

Well the main question here is: What answers did you consider, and how did you plan to deal with them? There is no hard and fast rule for the right place to invade in a situation like this.

Lets have a look at the position:

Click Here To Show Diagram Code
[go]$$c
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . w . . . . . . . . z . . . . . |
$$ | . . . . X x a b c d e f y X . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O O X . . . . . . . . . . . . . . . |
$$ | . O X , . . . . . , . . . . . O . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . O . O . . |
$$ | . . . . . . . . . . . . X X X O . . . |
$$ | . . . O . . X . . X . . . X O , O . . |
$$ | . . . . . . . . . . . X X O . . O . . |
$$ | . . . . . . . . . . . . . . O O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

To invade you would generally use the third line (the points marked a-f) or perhaps an attachment to quickly make sabaki (the points marked w-z).

All of these, I would consider briefly for their pros and cons, then I would read out the most likely variations for those I consider most promising.

So, some points to consider:
  • Where is black weakest?
  • Where do I have help?
  • Can I build a base anywhere, or make quick life?
  • Can I get out?

In this position, I would surmise that black's stones in the upper right are weaker than the upper left, and that help is closer at hand there.

To make a base, I would need the points a+d, b+e or c+f. There is no guarantee that I can make one, because black can always take the other. So then it is worth considering: What if I play one of these points, and black denies my base? Do I have a follow-up?

A plan with some promise, to me, would be to play e. This is close to black's weaker side, and if black denies me a base (by playing c), he's playing from his stronger side and pushing me towards his weaker side. I could make a one point jump into the center, and suddenly black's stones in the upper right are starting to look vulnerable.

If he defends them, I could follow by attaching on top of the pincer (c) and building towards the center from there.

One of the sequences I envision after the invasion would be:

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

Then I would read further options w.r.t. the cut at a, which when handled properly should give me options to jump to somewhere around b and counter-attack.

Of course, this is just one of the many options to consider. I would spend considerable time reading out the attachments w and x in a game.

Author:  Magicwand [ Wed Feb 06, 2013 8:50 am ]
Post subject:  Re: Question about invasion

below looks better than invasion to my eyes.
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . . . . . . . . X . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . 1 . . . . . . . . . . . . . . . |
$$ | . O O X . . . . . . . . . . . . . . . |
$$ | . O X , . . . . . , . . . . . O . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . O . O . . |
$$ | . . . . . . . . . . . . X X X O . . . |
$$ | . . . O . . X . . X . . . X O , O . . |
$$ | . . . . . . . . . . . X X O . . O . . |
$$ | . . . . . . . . . . . . . . O O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


if he answer as below..
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . . . . . . . . X . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . X 5 . . . . . . . . . . . . . . . |
$$ | . . . 1 2 . . . . . . . . . . . . . . |
$$ | . O O X 3 . . . . . . . . . . . . . . |
$$ | . O X 4 . . . . . , . . . . . O . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . O . O . . |
$$ | . . . . . . . . . . . . X X X O . . . |
$$ | . . . O . . X . . X . . . X O , O . . |
$$ | . . . . . . . . . . . X X O . . O . . |
$$ | . . . . . . . . . . . . . . O O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


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

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