(;FF[4]
CA[UTF-8]
GM[1]
GN[Becoming 9 Kyu - Lesson 37]
PC[https://online-go.com/review/432748]
PB[Black]
PW[White]
BR[2d]
WR[2d]
OT[Error: time control missing]
RE[?]
SZ[19]
KM[6.5]
RU[Japanese]

(;AB[lb]
;AB[lc]
;AB[mc]
;AB[oc]
;AB[od]
;AB[pd]
;AB[qe]
;AB[re]
;AB[rd]
;AB[sc]
;AB[sb]
;AW[qd]
;AW[rc]
;AW[qc]
;AW[qb]
;AW[pc]
;AW[ob]
;AW[nb]
;AW[mb]
;AW[ma]C[Hi! Let's solve some life and death puzzles! Look at this puzzle. Black wants to capture white. The difficulty is slightly higher than in previous lessons.]
(;B[pa]C[If you've solved many life and death puzzles, this move comes to mind instantly. This kind of move is usually good. But in this case it's a mistake, because of the special characteristics of the corner.]
;W[oa]C[In response, White will block here.]
;B[qa]C[Black has to try to connect like this.]
(;W[ra]C[If White captures these two stones,]
;B[rb]C[Black can cut and capture white. ]
;W[pb]C[After White captures them, ]
;B[qa]C[Black can kill the white group with a throw in.]
)(;W[rb]C[But instead of that, this move is wonderful.]
;B[ra]C[Black has to atari here.]
;W[pb]C[But what if White connects here? Black is short of liberties. ]
(;B[sa]C[Because of the nature of the corner, Black can't rescue the three black stones like this.]
)(;B[sd]C[So Black has to connect here first.]
;W[sa]
;B[ra]C[Even though Black recaptures,]
;W[qa]C[Black can't capture White's group. White now has two eyes. It's a failure. The placement at Q19 is often the answer, but not in this case. How should Black play then?]
)))(;B[qa]C[In this case, this attachment is an excellent move.]
(;W[pa]C[If White blocks here,]
;B[ra]C[Black connects.]
;W[rb]C[Because of White's liberty shortage, White can't atari here.]
)(;W[ra]C[So White has to play here instead.]
;B[pa]C[If Black comes out here, White's in trouble.]
(;W[rb]C[If White connects,]
;B[oa]C[Black can capture everything by playing here.]
)(;W[oa]C[So White needs to make an eye.]
;B[rb]C[But then Black can play at this vital point!]
;W[pb]C[After White captures these two stones,]
;B[qa]C[Black can throw in, same as before. In doing so, Black successfully captures white.]
))))(;AB[qb]
;AB[qc]
;AB[pd]
;AB[re]
;AB[qe]
;AB[pe]
;AB[pf]
;AB[og]
;AB[ng]
;AB[nf]
;AB[ne]
;AB[nd]
;AW[md]
;AW[mc]
;AW[nc]
;AW[pb]
;AW[pc]
;AW[qd]
;AW[rd]
;AW[se]
;AW[rf]
;AW[qf]
;AW[pg]
;AW[qh]
;AW[ph]
;AW[oh]C[Black must do something in the corner. What is it?]
(;B[rc]C[S17 is a good try. But it's too direct.]
;W[sd]C[White will connect here.]
;B[sc]C[If Black stretches,]
;W[sf]C[White connects again. Black doesn't have enough space to form two eyes in the corner.]
)(;B[sb]C[This jump is also a good try. The 1-2 point is often a vital point in corner life and death puzzles. But not here.]
;W[sd]LB[ra:A]LB[rc:B]C[White connects. And now A and B are miai. If Black takes one, White will take the other and poke out the eye space.re miai. If Black takes one, White will take the other, and poke out the eye space.]
)(;B[sd]C[A couple of you found this throw in. This is correct.]
;W[sc]C[White will capture this.]
;B[rc]C[Now this atari is working.]
(;W[sd]C[White must connect here, or Black will connect these stones to the living center group.]
;B[sb]C[Atari.]
;W[sf]C[Connect.]
;B[ra]C[And now Black can form two eyes with the second 1-2 point. As you can see in both puzzles, corner puzzles often involve a throw in.]
)(;W[sb]C[If White stretches here,]
;B[sd]C[Black will just connect to the living center group. This is what might happen in a real game, since Black didn't get two points in the corner.]
)))(;AB[sb]
;AB[rc]
;AB[re]
;AB[rf]
;AB[rg]
;AB[sh]
;AB[qh]
;AB[qf]
;AB[pg]
;AB[oh]
;AW[og]
;AW[of]
;AW[pf]
;AW[qe]
;AW[se]
;AW[sd]
;AW[rd]
;AW[pd]
;AW[pc]
;AW[nc]
;AW[mc]C[Black must live in the corner unconditionally. How should Black start?Black must live in the corner unconditionally. How? should Black start?]
(;B[qb]C[R18 looks promising.]
;W[qc]C[White would play here.]
;B[pb]
;W[ob]C[Black can make this exchange without worry. But continuing is hard.]
;B[ra]C[This move is necessary for two eyes.]
;W[sc]C[But White can take this vital point and start a ko.]
;B[pa]
;W[rb]C[Ko]
)(;B[qc]C[This is the correct first move.]
;W[qd]C[White must connect.]
(;B[pb]C[Next, Q18 is tempting indeed.]
(;W[sc]
;B[ra]
)(;W[ra]C[White should take this vital point so that Black can't form two eyes.]
(;B[ob]C[Black can try stretching out here.]
;W[qb]C[White would cut in reply.]
;B[rb]C[Blocking here will not succeed.]
;W[qa]
;B[pa]
;W[nb]
;B[sa]
;W[qa]C[Black dies.]
)(;B[qa]C[This move is another good try.]
(;W[rb]
;B[ob]
)(;W[ob]C[White would respond on the outside, lest Black find two eyes by playing here next.]
;B[rb]
;W[oa]C[Now Black has a liberty shortage and can't form two eyes. So it's not the answer.]
))))(;B[ra]C[The key move is this 1-2 point. As you can see in these puzzles, the 1-2 point often comes into play in corner life and death. This is because it's easy to make two eyes with the two 1-2 points.e puszzles, the 1-2 point is often comes into play in corner life and death. This is because it's easy to make two eyes iwith the two 1-2 points.]
;W[qb]C[Of course White can think about cutting in here to stop the eye space from growing. But Black has a plan for this.]
;B[pb]C[Just cut. :)]
(;W[ob]
;B[pa]C[White can't punish Black's descent here because of a liberty shortage. So Black lives in the corner unconditionally.]
)(;W[pa]
;B[ob]
;W[oa]
;B[nb]
;W[na]
;B[mb]
;W[ma]
;B[lb]
)))))