26 Feb 2010 1 Comment

Strategy Spotlight: Deep Invasion of Oversized Moyos

This week, we take a break from variations on corner josekis to investigate something that’s close to the mid-game. How does one make a deep invasion into a massive half board moyo?

Diagram 1

Consider for example, a San-rei Game, where black intends to build massive region on the top of the board. For most of us, such large moyos are scary objects. The calmest way, would of course, to recognise than one had already made significant profit:

Diagram 2

Something like diagram too might occur. Such a reduction would have little risk for white, and the result may even be considered rather advantageous. Black’s territory on top is certainly impressive, but white has gained a good amount of territory on both sides. Later, White can cut away black’s corner with a, and exploit the weakness at b for further invasion. However, for some players, the prospect of giving the opponent so much territory is, at the very least, psychologically bothersome.

So, what are the options for deep invasion?

Diagram 3.

The attach at 1 looks like a natural position. After black hanes, the hane at 3 is the natural move to seek survival….

Diagram 4.

However, with so much strength on outside, there’s good chance that black can kill white completely. White, of course, has other options, such as playing white 3 and black 4 in Diagram 3 and hoping to use the corner aji. However, white’s chance of living is never that great.

Diagram 5.

A better approach is to consider a capping play at 1. Obviously if black submits by playing at a or b, then white plays c and the resulting exchange gives him a much superior position to diagram 2. Black therefore, must cap at 2. White now returns to playing 3. When black hane’s, white crosscuts at 5. With the support of 1, the situation is significantly different.

Diagram 6.

For example, if black extends with 1. White exploits the circled stone to the max with the sequence 2-8. Whites resulting survival, of course, remains unguaranteed. However, the groups of stones is now rather resilient, with possibility to make eye space at A, B and C. Killing the group will be difficult.

Diagram 7.

Should black extend the other stone, white continues with 2-8. Once again, whites group becomes rather resilient to attack. Black may attempt a cap at a, but white has the ability to attach at b, and a good amount of eye space as well.

That’s not to say, of course, that white is completely out of danger. However, should white live, Black’s large sacrifice both corners would have conceived few rewards. If you’re a fun of a fighting game, you may like to try such an approach against an oversized moyo.

by Mile Gu in Strategy Spotlight