Six stones in a row on the second row die, but eight stones on a row live. Seven stones in a row depends on sente.
This applies to the life of a group which has no eyes and which has a solid row of connected stones on the second line. As long as the group is enclosed, the number of external liberties are irrelevant.
Even if Black has sente, White will end up with a straight-four eyespace, which is alive. The two x points are miai.
With seven stones and sente, White also ends up with a straight-four eye space, which is alive. The two x points are miai.
With seven stones and gote, White ends up with a straight-three big eye. After 5 White is dead.
With six stones, even with sente, White ends up with a straight-three eye space. After 4 White is dead.
But there is a condition for White to live.
Under the condition that White has stones at a and b, if White plays first, White can live. If Black plays first, White will have a ko to live.
by ChihChan
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