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

05 Feb 2010 2 Comments

Strategy Spotlight: Territory focused Chinese Fuseki

This week, we consider an unconventional defence against an enemy approach to a common pattern that arises from the Chinese fuseki.

Diagram 1.

When white makes the corner approach to reduce Black’s potential, the orthodox reply is at Black 2. What follows is a standard pattern that many of you would have mostly likely encountered, especially if you’re a fan of the Chinese fuseki.

At any rate, Black is usually satisfied with this result, white 7 looks reasonably cramped, and black has increased the potential territory on both the left side and the top right by playing either a or b. In either case, white generally needs to respond at c. Meanwhile, white cannot complain too much, since he must of had three free moves elsewhere on the board.

Diagram 2.

There are times, however, when Black might feel his behind in territory. Or perhaps, the moyos are just not that important. In these situations, Black can choose the unconventional move at 2.

Diagram 3.

White might first look at black in puzzlement. Surely he has made a mistake? White’s most obvious response is at 1, and if things proceed as in diagram 3, black cannot possibly be satisfied. The circled stone looks flat on the third line ineffective. Meanwhile, white’s shape is solid, and it looks like white has successfully neutralised black’s moyo. What could black be thinking with 2?

Diagram 4.

Diagram 3, in fact, is just wishful thinking on white’s part. Black 1 starts the small avalanche Joseki, making maximum use of his extra circled stone. After white 6, Black 7 is essential. Playing this move at a is also joseki, but a total mistake in this context.

Diagram 5.

When white continues the joseki with the cut at 2, black’s circled stone looks perfectly positioned. If it were not there, black would be forced to play 5 at 7, and thus allow white to seal off the top in sente. With the stone, however, is it white 2 and 4 that is under pressure. By Black 7, white has two unsettled groups against black’s one. What’s more, black has taken a solid corner. The ensuring fight will be in black’s favour, and white has been completely tricked. Note that if white a, black can counter with b. Black 7 can also be played at c, but white d is sente.

Diagram 6.

So what is white’s best response? To answer that, we’ll need to rewind to the beginning. Despite first intuition, white’s only choice is to hane at 3, and play lightly at 5. With Black 6, black has completed his goal of securing a significantly larger corner than diagram 1. The result, however, is not one-sided. White’s light group is difficult to attack. Later, white can protect his cur with the 7/8 exchange, and then press down with 9.

If the top right is unimportant, black 2 is well worth a shot. In all likelihood, the enemy will walk right into a small avalanche, and end up fighting for his life.

by Mile Gu in Strategy Spotlight