Is there an area so big that an invasion cannot be stopped?

Boidhre · Post by **Boidhre** » Mon Dec 09, 2013 4:49 am

daal wrote: I think you are phrasing your question wrong. You don't get guaranteed life anywhere. However, Yilun Yang has said something to the effect of: a space of 24 points on the edge where the invader has the possibility of threatening to escape to the center is sufficient for making a living group. He might even have said it was 21 pts (3 x 7), but I don't have the book with me atm. In any case, the point is that this space doesn't guarantee you life, but that it's not unreasonable to try to live there, particularly if you play right, making forcing moves to expand your eyespace etc.

Go for it!

I believe he said, provided no opposing stones within the area underneath the 4th line, you can live or you can escape. Or, with two moves in a row you can form a living group with a 3 x 7 block of room, if you want to look at it another way.

HermanHiddema · Post by **HermanHiddema** » Mon Dec 09, 2013 4:54 am

Click Here To Show Diagram Code: [go]$$W White to play and live $$ +-------------------------- $$ | . . . . . . . . . X . . . $$ | . . . . . . . . . X . . . $$ | . . . . . . . . . X . . . $$ | . . . , . . . . . X . . . $$ | . . . . . . . . . X . . . $$ | . . . . . . . . . X . . . $$ | . . . . . . . . . X . . . $$ | . . . . . . . . . X . . . $$ | . . . . . . . . . X . . . $$ | X X X X X X X X X X . . . $$ | . . . . . . . . . . . . . $$ | . . . . . . . . . . . . . $$ | . . . . . . . . . . . . .[/go]

Try this some time. It is very hard to live here, despite it being in the corner. In a similar size area along the edge or in the center there is no chance without grievous mistakes by black.

Abe Yoshiteru (9 dan pro) wrote an article about this corner in Kido in November 1995.

asura · Post by **asura** » Mon Dec 09, 2013 5:49 am

HermanHiddema wrote:Try this some time.

There is also a cheat code available

http://senseis.xmp.net/?BiggestCorner

paK0 · Post by **paK0** » Mon Dec 09, 2013 12:46 pm

asura wrote:
HermanHiddema wrote:Try this some time.
There is also a cheat code available
http://senseis.xmp.net/?BiggestCorner

Wow, that really surprised me, I though 3-3 would make life for sure, considering the fact that even with a 4-4 stone in place you can not kill that invasion(in a normal game) and it usually doesn't extend far enough to make contact with the wall

hyperpape · Post by **hyperpape** » Tue Dec 10, 2013 8:39 am

In a "normal" game, you can sometimes try to kill the 33 invasion. You just need a lot of outside strength to keep your opponent from running outward and trashing your position.

jug · Post by **jug** » Tue Dec 10, 2013 10:31 am

If you like you can try it out on DGS (though not real-time) with shape-games to live in the center:
http://www.dragongoserver.net/view_shape.php?shape=10
http://www.dragongoserver.net/view_shape.php?shape=16

skydyr · Post by **skydyr** » Wed Dec 11, 2013 10:11 am

hyperpape wrote:In a "normal" game, you can sometimes try to kill the 33 invasion. You just need a lot of outside strength to keep your opponent from running outward and trashing your position.

Agreed. I think beginners are often told it can't be killed because in the examples given, trying to kill results in a worse result, but it is possible to hold the invasion to one eye in exchange for the invader breaking the seal. Whether you can prevent them from getting a second eye afterwards in the center depends entirely on how strong you are there. Killing this can also be rather complicated, so it's much easier not to mention it until later, as the circumstances are relatively rare and up to a certain level, one is liable to let it live and end up with a much worse position than otherwise.

hyperpape · Post by **hyperpape** » Thu Dec 12, 2013 7:39 am

And here's an example of Takemiya killing the 33 point invasion: http://senseis.xmp.net/?TakemiyaMasakiK ... ntInvasion

moyoaji · Post by **moyoaji** » Thu Dec 12, 2013 9:27 am

hyperpape wrote:And here's an example of Takemiya killing the 33 point invasion: http://senseis.xmp.net/?TakemiyaMasakiK ... ntInvasion

Why am I not surprised that Takemiya would be the kind of pro who would know when he can kill a 3-3 invasion?

skydyr · Post by **skydyr** » Thu Dec 12, 2013 9:45 am

In that example, I think both players knew it could be killed, but that Okada used it as a sacrifice to enable a greater reduction from the outside than he would have been able to accomplish otherwise.

Shaddy · Post by **Shaddy** » Tue Dec 17, 2013 11:33 am

Moderately strong amateurs (5d+ on tygem and oro) know when you can kill a 3-3 invasion too.

Life In 19x19

Is there an area so big that an invasion cannot be stopped?

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