(;FF[4]
CA[UTF-8]
GM[1]
GN[Becoming 9 Kyu - Lesson 25]
PC[https://online-go.com/review/414221]
PB[Black]
PW[White]
BR[2d]
WR[2d]
OT[Error: time control missing]
RE[?]
SZ[19]
KM[6.5]
RU[Japanese]

(;AB[ns]C[

-- chat --
xesha: is it bad that i avoid ko like the plague every game
xesha: counting ko threats isn't the problem i have, it's misinterpreting a capturing race for a ko
xesha: sorry i don't want to distract your lecture
xesha: continue kind sir!
]
;AB[nr]
;AB[nq]
;AB[np]
;AB[op]
;AB[pp]
;AB[qp]
;AB[rp]
;AB[rq]
;AB[sr]
;AW[os]
;AW[or]
;AW[oq]
;AW[pq]
;AW[qq]
;AW[rr]
;AW[sq]
;AW[qs]C[Hi! Today we'll learn about making a ko. Here's a puzzle. It's Black's turn to make a ko. It's impossible to capture this white group unconditionally.

-- chat --
tpnZbonek: hello
umnikos: hi
mirreke: Hello
prosody: howdy
Mr.GoBoard: Have a good lesson
peri4n: black T4 white Q2 and black s1 -> ko
prosody: Black K10 → ko (but elsewhere)
]
(;B[pr]C[How about this placement then?

-- chat --
umnikos: Q2 right?
]
;W[ss]C[In this case, White will capture this black stone, producing another eye. Therefore, Black can't kill this group. But Black can make a ko.

-- chat --
umnikos: oh it's more than that...
]
)(;B[ss]C[If Black plays here,]
;W[pr]C[White can easily live by making two eyes here.]
)(;B[sp]C[Capturing this stone is the answer.]
;W[pr]C[Inevitably, White has to make two eyes like this.]
;B[rs]C[After that, this throw in is a tesuji.]
;W[ss]C[White will capture this black stone, but Black can capture this group if Black wins the ko. Let's look at another puzzle.

-- chat --
mark5000: No looking ahead!
]
;B[sa]
;W[ra]
;B[rs]
;W[qa]
;B[qr]C[It's a two-step ko.

-- chat --
mark5000: It's a two-step ko.
mirreke: ah
]
))(;AB[rf]
;AB[re]
;AB[rd]
;AB[qc]
;AB[rb]
;AB[ra]
;AW[sb]
;AW[qb]
;AW[pb]
;AW[pc]
;AW[qd]
;AW[qe]
;AW[qf]
;AW[qg]
;AW[rg]C[Black needs to live with a ko in the corner. It's hard to live unconditionally.

-- chat --
mirreke: but black needs to fill t3 and t1
mirreke: ?
umnikos: T17
]
(;B[sc]C[In this case, this atari is a good move.

-- chat --
prosody: hello xesha
]
(;W[sf]C[If White bends,]
;B[se]C[Black blocks here.]
;W[rc]C[White has to capture this stone.

-- chat --
gerrysw11: hello
]
(;B[fl]
;W[im]
;B[qc]
;W[cl]
;B[rc]C[

-- chat --
umnikos: should we be solving the other two puzzles?
]
)(;B[aa]C[After making a ko threat,]
;W[ba]
;B[qc]C[Black can recapture. Black still has a chance to live in the corner. There's a big difference between letting a group live and capturing it in ko. Likewise, death and conditional life are quite different. There's a saying, "Ko is magical." In fact, the meaning of a ko changes a lot throughout the game. The weaker players are, the more they tend to fear ko. But I advise you to enjoy ko. There's no need to avoid it.

-- chat --
mirreke: what do you mean by releasing a group?
xesha: ko death is a fate worse than life
mark5000: By releasing a group, I mean letting it live.
mark5000: Yes
tpnZbonek: ko is fun -_-
mark5000: Sometimes ko is the best possible outcome. You won't play at your best level if you avoid it.
mirreke: but it is so hard to find an count ko threats
mark5000: Even if you don't win the ko, the opportunity to have a free move is nice just by itself.
mark5000: Let's look at one more puzzle.
]
))(;W[rc]C[

-- chat --
tpnZbonek: well black can decide to let stones dye
tpnZbonek: and safe ko threads for another ko fight
mark5000: Prosody, yes, that looks possible.
prosody: :D
]
;B[sd]
;W[sf]
;B[qc]C[

-- chat --
prosody: Would White play T14? I may be mistaken but I'd use it as a threat after taking the ko
]
))(;B[rc]C[If Black connects here, ]
;W[sf]C[White will reduce Black's eye space.

-- chat --
mirreke: thats dead
]
;B[se]C[If Black blocks here,]
;W[sc]C[White removes the eye shape and captures the corner. It's a failure.]
)(;B[sf]C[Black can't enlarge the eye space like this either.]
;W[rc]C[White can simply capture this stone, along with the entire group. Because of that, Black has to make a ko.

-- chat --
xesha: hello
]
))(;AB[ir]
;AB[iq]
;AB[hq]
;AB[gq]
;AB[gp]
;AB[go]
;AB[gn]
;AB[hm]
;AB[im]
;AB[jm]
;AB[kn]
;AB[lm]
;AB[lo]
;AB[kp]
;AB[lp]
;AB[mp]
;AB[op]
;AB[nq]
;AB[nr]
;AB[ns]
;AW[mr]
;AW[mq]
;AW[lq]
;AW[kq]
;AW[jr]
;AW[jq]
;AW[ip]
;AW[jp]
;AW[jo]
;AW[jn]
;AW[in]
;AW[ho]C[Black to make a ko.

-- chat --
tpnZbonek: l3 first?
mark5000: L3 is in play.
umnikos: is the miai eye meant to be used as a ko threat?
mark5000: Good eye ;)
mirreke: N1 first?
gerrysw11: M1?
mark5000: Well, yes, those are the four possibilities. They've all been mentioned now.
mark5000: That's all I had prepared for this lesson.
mark5000: Any questions?
tpnZbonek: thanks for lesson
gerrysw11: thx, when's the next, please?
Burak23: Thanks 
umnikos: how to fight a ko now maybe?
mark5000: Next Saturday, same time.
prosody: Do you prefer seki over life by ko, or the reverse?
mirreke: thanks!
umnikos: and when do you fight the ko
LosesALot: ty
umnikos: do you leave it for endgame or rush it?
mirreke: how to count the value of a ko
gerrysw11: ty
xesha: woof i'm an american in korea right now
deepwell: ty
xesha: and i hope it will help :D
mirreke: I gues s the time to fight it depends on the value
mark5000: General preference is life > mutual life > conditional life > death
prosody: Thanks you :) for the lecture also, big thanks
mark5000: This lecture is part of my lecture series on becoming 9 kyu.
mark5000: Find past lectures here: https://forums.online-go.com/t/becoming-9-kyu-a-series-for-beginners/3809
mirreke: cool!
mark5000: There's a question how to fight a ko.
LosesALot: Egf?  
umnikos: (and when)
prosody: European Go federation, LosesALot
mirreke: european go federation
xesha: don't think fast just play fast, that's korean go at least
LosesALot: Ah, t
mark5000: To fight a ko, you have to change the board state so that you can recapture the ko without repeating a prior position.
LosesALot: Ah, ty
mark5000: Forcing moves that change the board state and enable recapture of a ko are called ko threats. I'm guessing most of you know this already.
xesha: this last bit on setting up a ko is super foregin to me
mark5000: The player who has more ko threats of greater value than the value of the stones in ko will win the ko.
xesha: that's really advanced, but also great info
xesha: thanks
mark5000: There's also the question when to fight a ko.
xesha: when or when not to use aji to gain threats
mark5000: At the kyu level, often you'll fight a ko when you stumbled into it.
xesha: @_@
mark5000: Or if your opponent left the option available to you and you find the correct sequence to make a ko.
umnikos: is death sometimes better than a ko when you can't afford to fight it?
xesha: i just avoid ko like the plague because its harder to predict my opponent
mark5000: Using aji to gain threats is a dan level topic. I don't think it's relevant to most players watching now.
prosody: experience tells me finding an eldritch ko threat that looks like it's not worth much at first sight but has far-reaching consequences is how you win games that you shouldn't in the high ddk-low sdk range
prosody: umnikos: if you can't afford to fight the ko, you get death anyway
mark5000: The general idea is when you see a ko is inevitable (through reading ahead), you can play elsewhere to complicate another local situation and make the value of moves in that local area bigger. Then you have more threats there when the ko arises.
xesha: hmmmm
xesha: i'll have to try that
xesha: i just read ko then panic into settling it
mark5000: It's common to panic, but there's absolutely no need. Ko is similar to any other board position. You have to find candidate moves, evaluate them, and choose the best option.
xesha: thanks mark!
xesha: I actually played in a korean kiwon today, i will be invigorated for tomorrow
mark5000: Good luck@
mark5000: Thanks everyone for watching. See you next week same time.
mark5000: For a joseki lesson.
]
(;B[ms]C[Black may also think about pushing here.

-- chat --
xesha: b n1?
xesha: it's funny seeing moves i've used as w but not seeing as b...
]
;W[ks]C[In response, White should not block but rather make an eye shape here. Black can't prevent White from making two eyes now.

-- chat --
xesha: hooooo
prosody: If a bad move by Black is answered by White at L1, try playing L1 ;)
]
;B[ls]
;W[lr]C[can't prevent White from making two eyes now.

-- chat --
prosody: wait no
]
)(;B[js]C[This move is tempting.]
;W[ks]C[White would block here.]
;B[ls]C[Black can think about making a ko like this. However,

-- chat --
prosody: damezumari
]
;W[ms]C[

-- chat --
lovecall: a. From move 0: J2 J3 H3 G3 G4 G5 G6 H7 J7 K7 L6 M7 M5 L4 M4 N4 P4 O3 O2 O1 N2 N3 M3 L3 K2 K3 J4 K4 K5 K6 J6 H5 K1 L1 M1 N1 
]
;B[kr]
;W[lr]C[Black can't connect. It's not a real ko.]
)(;B[ls]C[There's only two move choices left, and one of these placements is the answer. The one you choose makes a big difference.]
;W[ms]C[In this case, White blocking here is inevitable.

-- chat --
AresUII: Does n1 refute m1?
]
;B[js]C[Then Black can link up here, making a ko precursor shape.]
;W[ks]C[White has this throw in, however. Now the position is one we've seen previously. Now the opposition is one we've seen previously.

-- chat --
prosody: same chain atari as earlier though
]
)(;B[ks]C[This is correct. Black can only force a ko with this move.]
(;W[ls]C[If White makes eye shape,]
(;B[ms]C[Black pushes in here.

-- chat --
xesha: i get tricked by that shape every time
]
;W[kr]
;B[lr]C[Now it is ko.

-- chat --
mirreke: maybe I get to SDK EGF once ;-)
prosody: mirreke don't follow that link it's dangerous for you
]
)(;B[js]C[Drawing back here is a trick.]
;W[kr]LB[is:A]LB[ms:B]C[Black can't get both A and B.

-- chat --
xesha: yeah that one
]
))(;W[js]C[White can't block here, either.]
;B[ms]
;W[ls]C[Unlike before, this throw in is not working.

-- chat --
umnikos: thanks!
]
;B[lr]
;W[kr]
;B[ls]C[White dies. Therefore, ko is the best answer.

-- chat --
mirreke: If you can't win it, you get the compensation of the follow up to your last ko threat
mirreke: thank you
]
)(;W[ms]
;B[js]
;W[kr]
;B[ls]C[

-- chat --
mirreke: experience tells me I stumble mostly at the wrong time into it
]
))))