Invading deep enough

  Difficulty: Intermediate   Keywords: MiddleGame

This page deals with an invasion, which might appear even in an early stage of the game. It is especially likely in high handicap games.

Initial Position  

White was able to attack a 4473 enclosure with an ikken tobi and is faced with the question how to invade. He might boldly come in at a, or he might opt for the more quiet b.

b might be the "natural" choice of an intermediate player, but a was suggested by Takagawa Kaku, in a German book. (Band 16 der Schriftreihe des Deutschen Go-Bundes),

Main sequence:

crosscut 1  

This crosscut is an important position, which can be reached by both invasions. White might as well start with W3 and play W1 after the hane at B2.


If Black stretches at B1, White might choose the following sequence to settle his stones. However, he still needs to protect the gap at a, so Black will get sente.

White failure  

White is unlikely to get a better result from the crosscut, as this diagram indicates.

On the other hand, Black is unlikely to improve on the stretch too.

Avoiding the crosscut

a) light invasion

a1) Black alternative  

It seems like White will be able to settle his stones even easier than in the crosscut variation.

a2) White alternative  

White has settled his shape, but it does not look like a success to me. Warning: We still need the comment of a strong player on this variation!

Both players are likely to accept the crosscut when the light invasion is played.

b) deep invasion

b1) Black alternatives

Just the cross cut again  
Black failure  

If B3 is at W4, we have reached a special variation of the crosscut, but Black has already choosen the inferior atari instead of the stretch.

To be investigated.  

At least, Black seems to have this possibility to achieve a different crosscut, which might cause some problems.

To be investigated  

Maybe this works, but the ikken tobi is under attack now, so White will not be too happy.

What does White gain from offering Black this disturbing alternative option?
b2) white alternative

different hane  

Maybe this?


A) Takagawa Kaku presents the following position in a chapter about "How to answer a boshi":

Takagawa's diagram  

He mentions, that B1 should be at a, in order to prevent W4, after which he sees the black stone in the corner in a difficult situation. He does not mention a move at b.

After B1, W2 is a splitting attack. If Black had played B1 at a, he could easily respond to W2 with a play to secure the corner.

Almost Takagawa's diagram  

If Black moves out to the other side, W2 does not affect the left-hand corner as much as W2 in Takagawa's diagram did. The left-hand corner is more stable, and white+square is further away from it than white+circle from the right.

Not Takagawa's diagram  

A very similar problem was found in Pro common sense that even amateurs can acquire, which recommended B1. The reasoning was that moving out to the left or right (b or c, say) are approximately miai and so can be left for now; by playing B1, the dangers of B1-W4 above can be avoided.

Of course, Takagawa's comments on how to move out after a boshi are noteworthy, but we still have no clue why he opts for the deep invasion!

B) amateur game

from a nine stone handicap game  

Luckily not knowing Takagawa's proposal yet, White initiated the following sequence:

Game sequence  

This sequence is a success for White. He started out with a group of weak stones which are now living with territory. white+square is on a point that adds to White's good shape here; and White has sente.

The light invasion seemed to be okay. Black should have played B2 at W3, leading to the mentioned crosscut.

Contributed by:

Andre Engels Charles Floris kokiri Sebastian Karl Knechtel Klaus

Invading deep enough last edited by squadette on August 7, 2005 - 13:12
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