Eye shape, Eye space - Discussion
Below is a discussion of the difference between eye space, eye shape and eye potential
- Eye space is the space available for making eyes.
- Eye shape is the shape of the available space and its quality with respect to the objective of making (two) eyes.
- Eye potential is a measure for the likelihood of making eyes.
You can reduce eyespace, by playing a hane for example.
You can destroy eyeshape, by playing on the vital point.
The white group has lots of eyespace. But this space is also large enough for Black to build a living group, or at least a group with sufficiently good eyeshape to annoy White.
We cannot say that White's eyeshape is very good. The group consists of two straight lines.
White has now two eyespaces, one already being an eye, and one where it will be easy to make a second one.
Comment: This, OC, is nonsense.
RobertJasiek: Indeed. There is one eyespace consisting of two - as I call them - lakes.
This white chain is out into the open. It has an enormous amount of eyespace. Eyes can be made anywhere.
This group has the same amount of eyespace available, but has much better shape. The group will find it easier to make eyes, although the available eyespace is the same. As for the shape of the configuration, the shape of the group has changed, rather than the shape of the eyespace (although a change in the group composition, affects the composition of the eyespace and the other way round).
In this example, the Black stones make a nice shape. Without the marked white stones, the eyespace available is so vast that Black needn't worry about life.
With the marked stones present, the eyespace is greatly reduced, and now Black doesn't feel that comfortable anymore. A move at a, for example, could become annoying.
Eye potential could be defined as the likelihood for making eyes for a group. It is the combination of the space available to make eyes (eyespace) and the shape of the group with respect to the objective of making eyes (eyeshape). Eye potential grows larger when
- There are more than one eye spaces
- The eye space is larger (though there is a caveat)
- The shape is better
In tsumego, where there is usually one group surrounded by another, eyeshape, eyespace and eye potential can be used interchangeably.