(;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.

-- chat --
mark5000: o/
]
(;B[nc]C[

-- chat --
鄭會群: Hello
]
)(;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.

-- chat --
crusadergo21: S18
]
(;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.

-- chat --
mark5000: Nice job Daos88888 
mark5000: Let's look at some other puzzles. And I'll make these more interactive.
]
)(;B[pe]C[

-- chat --
鄭會群: 3. From move 0: M18 M17 N17 P17 P16 Q16 R15 S15 S16 T17 T18 R16 S17 R17 R18 Q17 P18 O18 N18 N19 R19 S19 Q19 P19 Q15 
]
)(;B[nc]C[

-- chat --
鄭會群: 4. From move 0: M18 M17 N17 P17 P16 Q16 R15 S15 S16 T17 T18 R16 S17 R17 R18 Q17 P18 O18 N18 N19 R19 S19 Q19 P19 O17 
]
)))))(;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?

-- chat --
mark5000: Any guesses?
cacoch: kill p16
Nilarof: s17 maybe ?
Nilarof: To try to live in the corner
layovah: nah he wouldnt be able to
Rimuru Tempest: i can't solve this at all :p
layovah: i dont think
cacoch: sorry r16
Nilarof: because there is a lot of forcing move with the white stones
layovah: if a 2k cant solve this i give up
mark5000: This puzzle is about 11 kyu level.
layovah: can you give us a hint
mark5000: Yes, Black can make two eyes with the two stones in the corner
Joseph146: Q19 maybe
mark5000: A 12 kyu already found the solution, but I'm ignoring it for now. :)
Cautiousford: S17?
Rimuru Tempest: args
Rimuru Tempest: i'm an idiot
]
(;B[sd]C[A couple of you found this throw in. This is correct.]
;W[sc]C[White will capture this.

-- chat --
Picard: t16?
Nilarof: Same as you show but with a t16 before ?
]
(;B[oc]
;W[ob]
;B[od]C[

-- chat --
鄭會群: 5. From move 0: R18 R17 Q16 S15 R15 Q15 Q14 P13 O13 O14 O15 O16 N16 N17 O17 Q18 Q17 R16 S16 T15 S14 R14 Q13 R12 Q12 P12 T16 T17 P17 P18 P16 
]
)(;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.

-- chat --
Hikaru_Shindou_: thats a good move
]
;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.

-- chat --
Nilarof: https://online-go.com/game/20971004
Nilarof: ups
Picard: 6. From move 0: R18 R17 Q16 S15 R15 Q15 Q14 P13 O13 O14 O15 O16 N16 N17 O17 Q18 Q17 R16 S16 T15 S14 R14 Q13 R12 Q12 P12 T16 T17 S17 T16 T18 T14 S19 
Hikaru_Shindou_: black lives
]
)(;W[sb]C[If White stretches here,

-- chat --
Nilarof: so the shape is better while you're ataring the groups
cacoch: 7. From move 0: R18 R17 Q16 S15 R15 Q15 Q14 P13 O13 O14 O15 O16 N16 N17 O17 Q18 Q17 R16 S16 T15 S14 R14 Q13 R12 Q12 P12 T16 T17 S17 T18 
]
;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.

-- chat --
mark5000: Let's look at another corner life and death that might involve a throw in ;)
Nilarof: But the other one is sente for white, so it's maybe better ?
]
)))(;B[sc]
;W[sd]
;B[rc]
;W[sf]
;B[pa]
;W[oa]
;B[ra]
;W[qa]
;B[sb]C[

-- chat --
Nilarof: how do you send variation ?
]
)(;B[rc]C[S17 is a good try. But it's too direct.]
;W[sd]C[White will connect here.

-- chat --
layovah: nice. you're sort of pre-setting a wall for white to run into
]
;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.

-- chat --
Rimuru Tempest: ofc
]
;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[sb]C[

-- chat --
sageb92: T189
sageb92: T18
]
;W[rb]
;B[rc]C[

-- chat --
sageb92: haha
]
;W[sd]
;B[ra]
;W[sc]
;B[qa]C[

-- chat --
sageb92: ;)
]
))(;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?

-- chat --
mark5000: Yeah, it would depend on all the circumstances.
mark5000: This puzzle is about 8 kyu level, so it's harder than the level of these lectures. But if you think hard you can solve it!
Nilarof: It doesn't feel like a good change of the position for black i think
Nilarof: The same, but with another stone for white
mark5000: I may have misled you. This one involves not really a proper throw in. It involves a cut that shouldn't work but it does.
mark5000: But playing it feels like a throw in and has the same flavor. :)
mark5000: Any first-move suggestions?
p6109: R17
Merlin77: r18?
Nilarof: yeah i also like q18
mark5000: Q18 will be met with R18, I think.
Nilarof: then r17 put pressure ont the 3 stones on the right
Nilarof: so white has to connect i believe
mark5000: It's important for this puzzle that N17 is on the third line
mark5000: If it were on the second line, the answer might well be the first ko we looked at.
mark5000: THanks for watching!
layovah: thanks for the lesson!
mark5000: This lesson is part of my lesson series for beginners: https://forums.online-go.com/t/becoming-9-kyu-a-series-for-beginners/3809
Nilarof: Thanks a lot for the lesson !
mark5000: They are weekly on Saturdays at 8:00am PST, or one hour ago.
mark5000: I hope you remember to live in the corner using throw ins and the 1-2 point.
ralph.tandetzky: Thanks!
mark5000: Or you can kill using the same tactics, as in the first puzzle
ralph.tandetzky: You're awesome!
]
(;B[qd]
;W[qc]C[

-- chat --
layovah: im guessing the throw in is at R16...
]
)(;B[pb]C[

-- chat --
Picard: Maybe?. From move 0: T18 S17 S15 S14 S13 T12 R12 R14 Q13 P12 P13 P14 Q14 R15 T15 T16 S16 Q16 Q17 O17 N17 Q18 
Picard: q18
]
;W[qb]
;B[qc]C[

-- chat --
Nilarof: or maybe not
]
)(;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.

-- chat --
p6109: thnks
]
(;B[pb]C[Next, Q18 is tempting indeed.]
(;W[sc]
;B[ra]C[

-- chat --
Picard: 8. From move 0: T18 S17 S15 S14 S13 T12 R12 R14 Q13 P12 P13 P14 Q14 R15 T15 T16 S16 Q16 Q17 O17 N17 R17 R16 Q18 T17 S19 
]
)(;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]C[

-- chat --
ralph.tandetzky: Black gets two eyes. . From move 0: T18 S17 S15 S14 S13 T12 R12 R14 Q13 P12 P13 P14 Q14 R15 T15 T16 S16 Q16 Q17 O17 N17 R17 R16 Q18 S19 R19 S18 P18 
]
)(;W[ob]C[White would respond on the outside, lest Black find two eyes by playing here next.

-- chat --
ralph.tandetzky: I see it coming. 
]
;B[rb]
;W[oa]C[Now Black has a liberty shortage and can't form two eyes. So it's not the answer.

-- chat --
ralph.tandetzky: Yep. 
]
))))(;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.

-- chat --
sageb92: got it
sageb92: its miai
]
(;W[qa]
;B[qb]C[

-- chat --
sageb92: S19
]
)(;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.

-- chat --
sageb92: just cut
]
;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.

-- chat --
layovah: cool
mark5000: That brings us to the end of this life and death lesson. Any questions about corner life and death principles?
Cautiousford: Could white play the atari at q19 instead?
]
)(;W[pa]
;B[ob]C[

-- chat --
mark5000: That would go nowhere, I think.
mark5000: Nice thought
]
;W[oa]
;B[nb]
;W[na]
;B[mb]
;W[ma]
;B[lb]C[

-- chat --
Cautiousford: Oh yeah.
]
)))))(;AW[mb]
;B[qc]
;W[qd]
;B[ra]
;W[qb]
;B[pb]
;W[ob]
;B[pa]C[

-- chat --
Cautiousford: Thanks so much.
Cautiousford: It was very enlightening.
]
)))