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Big eyes
Wolves are balanced formations, of which there are three types. We will call them Wolf-2, Wolf-3 and Wolf-4. The number refers to the number of Ӝ blocks of stones that can be removed with a single move Ӝ.
In general, a wolf has of a pair of Ӝ within it, with the following property: when captured, Ѡ the space left behind when the block is removed Ѡ needs at least one move to be made into two eyes. Blocks smaller than 3 decompose into Wolf-2(0) as their capture does not gain liberties (the 0 refers to the size of the block.) Wolves can also have tails (additional Ӝ.) The second and third number in brackets given below refers to the tail lengths. Zeroes may be omitted.
Wolf-2
This is the simplest and largest type, containing Wolf-2(n) where n = 3, 4, 5 and 6.
Wolf-3
Since capture of the tail must fail, we find (3, 1), (3, 2), and (4, 2). Tail lengths greater than 2 are indicated with a 2, as they behave the same, although a large enough tail causes instability (ie 2 more than the sum of the other same-coloured stones is enough to move with that colour). (4, 1) is only possible if the block is not 2 x 2 (block4), and the defender can find four ‘ko’ threats and make two approach moves. (4, 2) when at least one of the blocks is 2x2 (block4) on the edge is unstable unless the defender can find two ‘ko’ threats (two moves elsewhere that need an answer there) and make one approach move (a move that causes a repetitive cycle to become closer to endable).
Wolf-4
We have Wolf-4(3, 1, 1), Wolf-4(3, 2, 2), Wolf-4(3, 1, 2), Wolf-4(4, 1, 1) and
Wolf-4(4, 2, 2).
A Wolf-2(3)
A Wolf-3(3, 1)
A Wolf-4(3, 1, 1)