Two Eyes/ Discussion

Sub-page of TwoEyes

Bill: I put the discussion about life in a footnote because this is introductory material. The first thing a novice needs to know here is that you can make groups with two firm eyes that do not need to be defended. After that they need to know about groups that, when attacked, can make two firm eyes.

Grauniad: The fact that each eye in the diagram has only one point may be misleading to novices. I think this critical concept would be better demonstrated by discussion of a more general diagram in which at least one eye has more than one point. Something like this?

Two Eyes  

Bill: Why not both examples? :-)

Grauniad: What does the first add to the second? :-)

Bill: The first one is the prototype. The second one generalizes the first.

Robert Pauli: Honestly, Bill, this footnote style doesn't attract me much (and lost the seki case, BTW). Shouldn't it better (and without footnote) be something like

A group of stones is safe from capture (is alive) if it can not be prevented to reach seki or (more desirable) to form two eyes.

Crystal clear and to the point, not?

Bill: Charles Matthews prefers the term, safe, to indicate stones that are alive without defense. Not everybody uses it that way, but, since there is a reasonable (and traditional) alternative, alive, for stones that may require defense, I am happy to stick with the traditional term, and not equate the two.

Since this is introductory material, I agree that it is best not to get too technical. If it were about life, like the alive page, I would agree that a discussion of seki belongs here. But it is not.

Logically, your sentence is clear. Operationally, it gets into areas that are beyond the ken of novices. How do you reach seki or form two eyes? And it is not really to the point of this page, but of the alive page.

Robert Pauli:

  • Used "safe from capture", not "safe" on its own, but don't mind to change to "can not be captured".
  • Doesn't this page explain a term ? Shouldn't it be understandable and exact ?
  • Referring to "seki" and "alive" (not my idea, BTW) just gives the whole picture - this page's topic is "two eyes" and has to be pinned down here - where else ?
  • To rule out the stuff I put on Smallest Group with Two Eyes, I'm thinking about something like
    • "has two eyes" (normal sense, one case of "alive", being able to convert to the strict case below) and
    • "strictly has two eyes" (eyes minimal, each part touching at least two - safe in CM's sense)

Two Eyes/ Discussion last edited by RobertPauli on October 18, 2017 - 15:46
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