RTG Problem 35 / Solution
The best Black can get is to connect back the two Black stones in sente, leaving the endgame benefit of capturing two White stones at a.
Note that in this diagram, both
and
are tesuji.
Note that
cannot hope to save the two White stones.
is a good move, and White is killed.
and
are tesujis, because
cannot cut directly.
captures all the Black stones.
is dangerous.
and
eke out a ko, and the life and death of the entire White group now depends on this huge ko.
Similarly,
here is also very dangerous. After
, White can only live by a ko.
forces
, and looks like
is a tesuji that kills?
If
, then
crawls and connects out.
But
can simply descend. With
, Black happily sees the stones coming home. And then
squeezes. White has in fact prevented the guest (three Black stones) from leaving!