Bill: Howard Landman, in his "Eyespace Values in Go" paper in "Games of No Chance", defines topological life this way: A group is topologically alive if and only if the chains of the group surround more than one one-point eye, and each chain reaches more than one of those eyes. That covers two headed dragons nicely. :-)
Tas I just wanted to add my own way of determining whether a group is alive or dead when "seemingly-false-eyes" are involved. If surfed around the pages on this subject for a while now, and I can't find that anyone else has written this before, so now i do. If I'm wrong, please correct me. I this belongs at another page, please tell me or move it.
I simply check if all separate strings of the group in question attach to at least two "eyes" (whether false or not, or "just connections"), here included all strings touching the "eyes" in question of course.
I don't think this method ever fails.
If the eyes are too big, or this criterium isn't satisfied but there are outside liberties (escape?) this method considers it unsettled and reading and intelligence are needed off course.
Aarh.. this doesn't read nearly as simple as it is in my head...
And how about this one? A baby dragon? ;-)
No, I would consider these two normal eyes, not two 'seemingly false' eyes. The 'missing point' is not under white's control. -- Andre Engels
'Missing point'? Anyway, I just brought it up because I think these eyes are as false as those in the first diagram.
Shike: Yes, and it's a cute dragon too^^. Very strong for that size...
iopq: Each eye's diagonal space is surrounded by at least 3/4 non-white pieces when rounding up. Therefore it's no baby dragon.
iopq: As long as there is no WHITE stone in a it's not a false eye.