Episode #4 A perfect base?
Hello everybody.
Many of you will recognize this position, which comes from one of the most basic joseki patterns in go.
In this episode we will focus on white's base: its benefits and weaknesses.
What sort of aji can black still expect to exploit from this classic white shape?
And what kind of black moves are good in which positions?
Let's go!
Depending on the surroundings and the overall board position, black has all sorts of aji moves: from [A] to [E].
These different techniques have different objectives, ranging from pressing white down and making moyo to attacking the base itself.
Let's start with option [A].
This move is called the [shoulder-hit].
This technique is especially useful for pressing down a larger formation of your opponent, which in this case would be on the right side.
It aims at reducing.
For example, imagine white has more stones on the right and lower side.
He is threatening to create a large moyo if he gets the chance to jump at [A]..
..or if he simply defends his right side in a more solid way, like [B].
In such a case, [this shoulder-hit] by black is the ideal move to press down on white's formation.
It prevents white from making his framework even bigger.
Maybe you can remember this move by visualising the meaning of the term [shoulder-hit].
The move is called a [shoulder-hit] since it seems to lean and put all its weight on the axis of white's framework.
Its shoulder: [A].
If white does not react and lets black lean on his shoulder even more..
..the weight becomes too much and white's position collapses.
Not only does this move put huge pressure on the three white stones at the top - they are severely hurt - it is also very big in itself in terms of destroying the white territory on the right side.
The usual way to respond to this kind of [shoulder-hit] is by trying to push the opponent off your shoulder, by playing either [1] or [2].
White pushes black back in an attempt to get the big weight off his shoulders.
This is one way of playing [lightly] and defending the territory on the right side.
Another technique.
Black succeeds in pushing white down, but white takes a lot of solid territory.
Option [A] is for reducing. Let's see [B].
One of the other most frequently used techniques in this shape also involves a pressing strategy.
Black forces white to react and defend his base.
And then black finishes off his shape by playing this contact jump.
This technique aims at pressing white's base down and at the same time creating a wall for black that exerts power towards the left side.
To give you a better idea of when to play such moves, let's see another overall board position in which this sequence can occur.
In this position black has a big framework on the top side.
Here the pressing move of black is extremely effective.
Not only does black limit white and press him down, he also creates a huge wall which cooperates with the rest of his moyo.
This technique is usefull for [expanding] your moyo.
White usually plays here in order to prevent a black hane at [A].
Black has several options now. He can play tenuki, or strengthen his wall choosing from [A] to [D].
We've seen two black moves that press white down from the outside.
There's one final pressing option at [C].
Combining the two ideas of black's reducing move at [A] and his moyo technique with [B], creates P10.
This move is especially powerful in situations where both players have big frameworks facing eachother.
Here both the situations of the two earlier pressing moves of black [A] and [B] have been combined. Both white and black have big moyos on either side of the board.
In such a case, [this move] can be very handy.
White's most standard answer would be to jump here, protecting his framework on the right.
However, now black combines his P10 move with the moyo technique we showed earlier.
Black presses white down and forms a magnificent wall at the same time.
Black's exchange of [1] for white [2] is ofcourse extremely good for black now, serving the purpose of creating a framework on a large scale.
White [2] is relatively low.
However, instead of reacting in the most obvious way, white can also fight back.
Danger! Tricky road ahead!
This prevents the previous variation where white got flattened.
Now black will probably play over [here]. A mutual destruction of frameworks will follow.
See [bonus sgf file] for a game between [O Meien] and [Kato Masao] where this sequence is played.
So far we've seen three techniques that black can use to press white's group down and to make a moyo of his own.
But what happens if white's 'perfect base' is pressured from the side?
What happens if there already is a stone at [A]? Which variations can we expect?
The first major idea is to attach [here]. How does white react?
The following variations are taken from "Think like a Pro: Haengma" by Young-sun Yoon 8p, published by Oromedia in 2006.
[This] move looks natural, but it's wrong!
The main idea behind the contact-play of [A] are the follow-ups with these kind of [cross-cut tesujis]
Such a [cross-cut] creates a miai situation for black. Black will be able to atari at either [1] or [2], splitting white into two.
This result is very good for black. His territory is huge.
This is also usually good for black. This [ko] is a huge burden for white. And white's territory has been hollowed out from the inside.
The ko is way more important for white than for black.
The other hane, from above, also looks natural. But again, it's wrong.
Black's group on the side is already alive. And black can cut!
This fight is very difficult for white.
Now that we've seen both hane's are wrong for white, let's see the correct answer.
[This] is the correct defense.
The move looks strange at first, but it's highly effective.
If black plays hane, white can block!
Miai. White can connect with either [A] or [B].
Instead of the hane at [A], black can play a testing move first.
[This] testing move asks what white wants. White wants to block firmly, leading to an atari for black.
This result is the best for both sides. White is solid but low. Black gains strength on the outside in sente. He can play [A], [B] or [C], all in sente.
Apart form the contact play at [1], black can also choose another [sacrificing technique].
There are many variations that start with this move, showing that there is still a lot of aji in white's formation.
We will show you a few of the most standard ideas.
Blocking [here] is natural.
Playing here immediately is a [sacrificing technique] by black.
Black's two stones are captured, but black will [squeeze] and gain something on the outside.
White takes the two stones.
Playing this atari first is crucial.
White has captured the two black stones, but black gains a lot of strength on the outside.
Instead of sacrificing the one stone immediately, black can play a [probe] first.
Black has this tesuji, leading to a lot of complicated variations.
If you like these kind of complicated fights, there is a lot to study here from pro-games.
If white blocks the main idea is that black has this tesuji.
If black is too strong in the surrounding areas and white wants to keep it simple, he can also play over [here].
This keeps it simple. White secures his base, but black gets a lot of points.
We have shown you most of the basic aji that occurs in this white shape so frequently called the 'perfect base in go'.
What about this formation in relation to [endgame]?
Many of you know that this move is big in late middlegame, or endgame. But how big exactly?
According to the book "100 tips for amateur players" by Young-sun Yoon 8p, this move is worth about 14 points.
This ofcourse also depends on the stability of both black's and white's group.
To give you an idea of the added value of [A]: do you know how big the follow-up at [B] is?
This is the normal follow-up. It's huge endgame! This move is worth 12 points.
Instead of the usual endgame, black can sometimes play a tesuji that is even bigger.
A special follow-up. This can be severe.
This move can be played when black has supporting stones around [A].
To end this episode we would like to show you it's always interesting to think outside the box.
There was one professional player who played [here]!
We think he was scared.. This removes a lot of the aji in white's base, but it's ofcourse extremely slow.
You can view this interesting but strange move in the episode's [bonus tab].
We hope that in this episode you have found some inspiration for dealing with 'the perfect base'.
Thank you for watching and see you next time!