TJ: Something I point out to beginners, which seems often taken for granted as known, about forming eyes. If a group has more territory, it is more likely to be able to live if invaded. Whether it can live or not depends on shape. If the shape is seven points of territory or more, it cannot have its eye space compromised with correct defense, and can make two eyes.
- Bill: Sorry, TJ. That's not true. What is true is that a solidly connected group with an eye of at least 9 points can live. (With only 8 points in the corner, ko is possible.) But that life might be seki.
- TJ: Don't be sorry...show me!:) The eye space page lists only one seven point shape which can be made seki (butterfly seven) as of this writing, and no eight point shapes, which even then is more than I've learned from other sources.
- Velobici: There is one group with all its stones solidly connected one to another that lives or dies according to who plays first. It is the Carpenter's Square. Please note that the group is not connected to the edge of the board on either side. So it most likely does not fit Bill's concept of solidly connected.
- TJ: Carpenter's Square isn't a group with a single completed eye of undetermined status yet, though. The groups I was mentioning, of shapes from 3-6 points, is meant to refer to such sealed-in, completed eye shapes, and how to determine status...do you have to play to live? Can you defend if attacked? Where is the vital point? Next step is looking at: Where is the vital point GOING to be when the group is totally sealed on all sides, and can I play there? Can I avoid making bulky-five in gote? Is it going to be square four if I play (move)? I mean to be talking about the basic shapes which groups which become cut-off get ultimately reduced to. What is the appropriate term to refer to this sort of basic shape concept? Eye space is maybe ambiguous, is that the source of confusion? Eye shape a better term? Help!:)
Less than seven points, it depends on shape of the territory surrounded. So, a good starting point for beginners is to learn the status of the territory shapes between three and six. That's not such a huge task, and makes all that life and death stuff you keep hearing is so important a lot more comprehensible; not to mention stopping you from considering attacks that just won't work and freeing you to look elsewhere, and helping you stop wasting time with over cautious defense of perfectly safe groups in your games. On SL, check out Eye Space to learn all about these important shapes.
Further ramifications directly deduced from this once the shapes between 3 and 6 are understood: Problems of Life and Death, both as exercise and within games, boils succinctly down to: Can a group can be cut off, and the territory it holds reduced to less than seven points of a shape which can be killed (death)/can such an occurance be avoided, or made to depend on the outcome of a Ko which will give the group life if won or give the player compensation for the killed group if lost (life).
Capturing races are just a form of the same thing in which two opposing groups are trying to live/kill each other at the same time.
Is this a good concise way of talking about what eyes are all about, and how to learn about them? If this is off topic, or is better stated elsewhere, or just too long winded, forgive me...I'm new here.:)
TJ: Given the discussions can I re-edit this to read something like:
- ...if the shape is seven points of territory or more, it can be defended to a minimum of life in seki or can form a ko. For large-eye shapes which can be reduced to seki or ko, find examples at Nine Point Eye - Possible Seki, Bulky Eight in the Corner, Butterfly Seven.
And then carry on with the rest pretty much as is?