gostudent wrote:
When I reviewed my games that I lost recently, I realized that there is a common theme: I often pick a wrong spot in invasion or in reduction, leading to either dead groups or my opponent get a lot of points elsewhere.
An example is the following. I invaded at (a) in the game, but that gave black extra points in the bottom, as black pincered at (b) subsequently.
I have three questions.
(i) Is it right for black to invade at the bottom?
Maybe.

But note that if White seals the corner with E-03, Black can still reduce the White framework.
Quote:
(ii) If black wants to invade at the bottom anyway, what would be some good options?
Too many possibilities. In a game that takes an hour, it would be reasonable to spend several minutes on this position.

Quote:
(iii) How can one become better in judging when to invade, and once invaded find plays to make enough shapes to live?
To quote Watson, THINK!

Judgement does not come easily. Experience matters. Try ideas out.

Don't be greedy.
One important point is that you do not have to live.

You can sacrifice stones for aji. You can live with some of your stones, while you give up others.
- Click Here To Show Diagram Code
[go]$$Bc Did it go this way?
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There is your invasion and his pincer.

If it did go that way, I think that

was a mistake. (

, I don't know.)
- Click Here To Show Diagram Code
[go]$$Bc Better
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$$ | . . 2 . C . 3 . b a . O O X O . X . . |
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After

I think that

is the play. For one thing, it has a possible extension to "a". For another, it is lighter than F-03. Also, it has a diagonal relationship to

, indicated by the marked points. (One reason that the diagonal relationship is important for sabaki is to make eye shape.

) Important point: You do not have to save

. It has done a good job by inducing

.
- Click Here To Show Diagram Code
[go]$$Bc Miai
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$$ | . . . . . . 3 . . . . . . . . O X . . |
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$$ | . . . . 2 . 1 . . b . O O X O . X . . |
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Another thought is to invade at 1, making miai of "a" and "b". One thing. If

,

may be better than "b", because White is so strong to the right. Not exactly miai.

Note that

has a diagonal relationship with

.
- Click Here To Show Diagram Code
[go]$$Bc Reduction
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$$ | . . b . 3 . . . . . . . . . O X . . . |
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Another idea is a reduction with

, aiming at 2. Now if

, Black can jump out with

(diagonally related), which aims at "b". Black still has play on the bottom side, at "c" and "d", for example (all diagonally related).
All of these plays are diagonally related to the same points. There is another set of possibilities diagonally related to "a".
