Vital point method simplifying the outside

Vital point  

If you are confused by or find it difficult to see where the vital point in a shape is, try to look at the internal space left over after the opponent has reduced the internal space from the outside. In this case, after Black's reduction (from the outside) and White's answer, the internal eyespace will be the circled points - which is recognisable as the bulky five - and the vital point is the same as for a bulky five.

(Anyway, it often helps me, maybe others have better/easier ways of seeing this --MortenPahle)

How do you get to this shape? When I look, I find it more logical to imagine black a and white b than the other way around (black b is clearly got, black a not), which gives another bulky five with its vital point at 1-2 rather than 2-2. - Andre Engels

Vital point?  

reduces White's formation to the bulky five and then plays on its key point. Since it threatens to connect, White responds with , threatening , which prevents.

White lives  

But now lives.

However,

Vital point  

Black may approach from this side and then strike at the vital point with . threatens to live with , which prevents. Then White captures Black's two stones with .

White dies  

But now prevents a second eye, and White dies.

(Not that White can live by playing first. ;-) See the L group pages.)

White lives  

After White has eyes at a and , thanks to .

comparison: white lives by playing a not b  

xela: Although I think the general principle stated at the top of this page can be useful, I find this particular example confusing. To me, the important feature of the first diagram is the white hane at the top. If that stone is removed and there is a hane at the right instead ( in this diagram), then the vital point is at a.

Black to play and kill  

If black were to reduce by playing a, then after white b the eyespace is three in a row, so c is the vital point--but black a allows white to live. Black can kill by playing on the vital point immediately.

Play on the vital point first: white dies.  

This reminds me of the One-Two-Three. -KenKennedy