Placement Principles
DrK (17k): Hi can a strong player have a look at what I've written please. These reflections just kinda come to me when I was studying Tsumego today...
General Principles in Placement
Like all kinds of tesuji, placement is one tool in a sequence of move that achieves something in a given position. However, there are some general principles that we can have in deciding whether a placement move is or may exist and therefore worth looking further.
Principle 1. Maximises liberty of your placement group
Example:
This is a standard life and death shape Carpenter's Square that if played correctly leads to a ko fight and for black, correct play begins with a placement. The more liberties the harder it is to be killed. The aim is to live as long as possible. This principle not relevant when the placement is a sacrifice (see Principle 5).
Principle 2. Try to make an eye
Obviously if you can make 2 eyes do so. But in a situation where the placement cannot live by itself inside the territory of the opponent's group, having an eye may decide the outcome of the situation. Using the previous example, suppose the opponent unwisely play elsewhere:
threatens to create an eye at square (and in fact kills white unconditionally).
Using the same reasoning,
The correct is to play underneath
. This move seems unusual (placement within a placement) until one realise that
-
removes the possibility of black making an eye
- Reduces liberty of
-
is gote connected to the white group.
Principle 3. Keep your placement group into a dead shape
Black is a bent four in the corner dead shape. If he plays at square in the next move he makes a bulky five which is dead standing. However if he plays at circle his shape is live and white can capture it and live.
This simplistic diagram illustrates how, instead of looking for live shape, one wants the opposite aka dead shape in relation to placement group that cannot live on its own. e.g. straight three, bent four in the corner, bulky five... etc so that the the opponent is forced to capture and end up with a territory that is a dead shape. This does not necessarily mean death for opponent's group but it at least force further play (e.g. escape into the centre, link up with another group, kill outside group) to live.
Principle 4. Be aware of opponents' group(s) with 3 or potentially 3 liberties
A group of stone is oiotoshi-able if it somehow ends up with 2 liberties. Since no matter how brilliant a move is, it can only ever reduce the liberty of a group of stone by one at a time. Therefore, a placement that leads to oiotoshi requires the prerequisite that the targeted group of stones has 3 liberties to begin with (or you can reduce it to 3 liberties by some mean).
The correct move begins with , which makes no sense until one sees it as a way to force the white stones to end up with 3 liberties.