Re: Why is white dead? II
Posted: Mon Jul 15, 2019 11:42 pm
To confuse you even further: things are clear when a group consists of only one string. In the diagram below, "a" and "b" are eyes because they are adjacent to the black string, and only to it.
When there are two strings:
"a" and "b" are eyes because each of them is adjacent to each black string and only to them.
A group can have two eyes that look like false eyes:
https://senseis.xmp.net/?TwoHeadedDragon
There are two eyes because the black group consists two strings, and "a" and "b" are empty intersections which are adjacent to each of these two strings and only to them.
On the other hand, in the original diagram there are three strings
but Black cannot play immediately at "a" so we can suppose that "a" is white, so we get two strings
The eye "b" is adjacent to only one string, so the group doesn't have two eyes. Another way of seeing this is to fill external liberties with enemy stones
and see that the lower white group is in atari.
(All the above is pretty obvious for experienced players, however it is not uncommon for SDKs to confuse false eyes with real eyes during a game... including me...)
When there are two strings:
"a" and "b" are eyes because each of them is adjacent to each black string and only to them.
A group can have two eyes that look like false eyes:
https://senseis.xmp.net/?TwoHeadedDragon
There are two eyes because the black group consists two strings, and "a" and "b" are empty intersections which are adjacent to each of these two strings and only to them.
On the other hand, in the original diagram there are three strings
but Black cannot play immediately at "a" so we can suppose that "a" is white, so we get two strings
The eye "b" is adjacent to only one string, so the group doesn't have two eyes. Another way of seeing this is to fill external liberties with enemy stones
and see that the lower white group is in atari.
(All the above is pretty obvious for experienced players, however it is not uncommon for SDKs to confuse false eyes with real eyes during a game... including me...)
