Re: Lake, Nakade, Eye, Eyespace and Related Terms
Posted: Sat Nov 09, 2013 3:05 pm
hyperpape, since I may not explain the degree of imprecision in this thread, please see here:
http://www.lifein19x19.com/forum/viewto ... 02#p152402
"Visually surrounded" could be made reasonably precise by referring to hulls constructed from the defender's bounding stones, where bounding is defined trivially a la Pauli.
Defining "can easily become" is trickier. I am not sure yet if this needs or can avoid "force".
"Visually surrounded" is used, because the concept 'lake' is a pragmatic means meant to help pruning reading. For this purpose, "visual" is good enough precision. If much greater precision is needed, one can fall back to the concept 'potential eyespace' and to more detailed reading. Potential eyespace has another informal definition and is also a pragmatic concept. If necessary, we fall back to even more detailed reading, which is defined precisely somewhere.
If a lake IS visually surrounded, things are easy. Not all lakes are easy, but there are lakes with open ends or gaps in the visual surrounding. For these circumstances, "or can easily become" is also needed. The gaps must, however, not be so big, loose and wide that nothing is meaningfully surrounded. There must at least be a principle perception of of surounding the lake easily.
Currently, the conditions for such surrounding are undefined. OTOH, one can construct such conditions using hulls again and allowing the defender successive imagined plays along a hull's boundaries.
Well, if you really want it done by formal research. As I say, lake is a pragmatic concept, as are 'potential eye' and 'potential eyespace' at the moment. I am satisfied if they are just big enough to include every relevant intersection. it is like for local move selection, which also relies on a big enough set of local intersections to be sure not to miss any relevant intersection.
Are you not used to my occasional use of fuzzy concepts?:) Fuzzy is not 'guessing' but is 'safe approximation'. Like nigiri: if you put your hand into the bowl, you will surely fetch at least a few stones, and this is good enough to guarantee a working procedure; it suffices to avoid fetching only zero stones. If only our regions are large enough, the relevant intersections will be in them.
http://www.lifein19x19.com/forum/viewto ... 02#p152402
"Visually surrounded" could be made reasonably precise by referring to hulls constructed from the defender's bounding stones, where bounding is defined trivially a la Pauli.
Defining "can easily become" is trickier. I am not sure yet if this needs or can avoid "force".
"Visually surrounded" is used, because the concept 'lake' is a pragmatic means meant to help pruning reading. For this purpose, "visual" is good enough precision. If much greater precision is needed, one can fall back to the concept 'potential eyespace' and to more detailed reading. Potential eyespace has another informal definition and is also a pragmatic concept. If necessary, we fall back to even more detailed reading, which is defined precisely somewhere.
If a lake IS visually surrounded, things are easy. Not all lakes are easy, but there are lakes with open ends or gaps in the visual surrounding. For these circumstances, "or can easily become" is also needed. The gaps must, however, not be so big, loose and wide that nothing is meaningfully surrounded. There must at least be a principle perception of of surounding the lake easily.
Currently, the conditions for such surrounding are undefined. OTOH, one can construct such conditions using hulls again and allowing the defender successive imagined plays along a hull's boundaries.
Well, if you really want it done by formal research. As I say, lake is a pragmatic concept, as are 'potential eye' and 'potential eyespace' at the moment. I am satisfied if they are just big enough to include every relevant intersection. it is like for local move selection, which also relies on a big enough set of local intersections to be sure not to miss any relevant intersection.
Are you not used to my occasional use of fuzzy concepts?:) Fuzzy is not 'guessing' but is 'safe approximation'. Like nigiri: if you put your hand into the bowl, you will surely fetch at least a few stones, and this is good enough to guarantee a working procedure; it suffices to avoid fetching only zero stones. If only our regions are large enough, the relevant intersections will be in them.