(;FF[4]
CA[UTF-8]
GM[1]
GN[]
PC[https://online-go.com/review/27504]
PB[Black]
PW[White]
BR[8d]
WR[8d]
OT[Error: time control missing]
RE[?]
SZ[19]
KM[6.5]
RU[Japanese]
C[

-- chat --
trohde: thanks again, xhu98!
xhu98: You are welcome trohde :)
Krakangel: Thank you for your work !
]
(;B[pd]
;W[nc]
(;B[oc]LB[dd:B]LB[jd:A]C[[Beginners tend to kick here, without knowing it's not good unless Black has a stone around A. So...\]
-----------------------------------
Yes, the kosumi joseki is most useful when Black has surrounding forces. For example, if Black plays a San-Ren-Sei opening (the other two stones are on A and B, respectively), the stone at A then prevents White from making a comfortable three-space jump and thus a good settlement.

For more study on this joseki paired with SRS openings, check out my recently scribed lecture at http://online-go.com/review/27131.]
;W[nd]
(;B[pf]
;W[jc]LB[qc:A]C[[Here I believe an invasion at A is possible. If it is, how can that invasion work? Can you give a few example sequences to have an idea?\]
-----------------------------------
The invasion will depend on Black's surroundings. Many players hate the kosumi joseki because there is too much aji in the corner. The key here is, however, that Black is NOT putting a focus on the corner territory by playing this joseki; had he originally played at 3-4 and followed the same sequence, his corner would be surely protected The star-point variant, thus, emphasizes more on the potential of expansion and attack, which seems more ambiguous and subtle.]
;B[pp]C[For example, if Black tenukis elsewhere...]
;W[qc]C[The invasion at 3-3 is now available for White.]
(;B[qd]C[Conservatively, if the top White group is very strong, Black can block at 9 and choose to give away half of his corner.]
;W[ob]
(;B[pb]C[Black can play the hane here...]
;W[pc]
;B[qb]LB[nb:C]LB[rb:D]LB[rc:A]LB[od:B]C[Black 13 is valid as Black will connect at B if White dares to play at A, and he can take either of White's two weaknesses (C and D.)]
;W[od]
;B[rc]C[End of joseki. White gains sente while Black manages to keep half of his corner. Both sides hold structures that are acceptable.]
)(;B[pc]C[Alternatively, if Black plays at 11...]
;W[pb]C[White crawls one more stone into the corner.]
;B[qb]LB[mb:A]LB[rb:B]TR[qc]LB[rf:C]C[Black captures the triangled stone, and reserves the right to peep at A. However, as White has a three-space jump already, Black's peep might not be so potent as White's counterattacks at B or C.

I myself somehow prefer this variation for Black, but just personal opinion.]
))(;B[ob]C[If Black extends at 9 and denies White the second-line connection, he will give White extra advantage to clinch the corner. However, this also means that the top White group (depending on local conditions) is more vulnerable to attacks.]
(;W[qe]C[White's peep at 10 is a good move.]
;B[pe]
(;W[qf]C[White 12 will concentrate more on the side.]
;B[qd]
;W[rd]
;B[qg]C[Black 13-15 explores White's shortage of liberties.]
;W[rg]
;B[rc]
;W[re]
;B[qb]
;W[qh]
;B[pg]C[White successfully steals more than half of Black's territory and gains sente, but he will actually need one more move on the right side to reinforce his group. Plus, Black has grown a lot "thicker", which can be game-changing especially when White is weak on top.]
)(;W[rf]C[If White tries to avoid the push-and-cut...]
;B[qf]C[Black 13 is a smart move.]
;W[re]
(;B[rg]C[If Black blocks right away...]
;W[rb]C[White makes life at the corner. Black leaves sente albeit with weaknesses at A or B (when ladder is in White's favor.)]
)(;B[qh]C[Black can also choose to avoid the weakness (as shown in the previous variation) by jumping out.]
;W[qb]C[White lives. Black gains sente, and both sides can be content with the fast pace. In this case, if Black has a stone at the triangled position, he'll find himself in a coherent setting.]
)))(;W[re]C[The knight jump for White is not the best here, because...]
;B[qe]LB[rd:B]LB[rf:A]C[The bulge move at 11 is crucial. White won't be able to extend at A because Black can touch down at B.]
;W[rd]
;B[rf]
;W[rb]C[White lives at the corner in gote. This is a less comfortable choice for his invasion.]
)(;W[rf]C[The monkey jump will not work either for White.]
;B[qe]C[As long as Black occupies the vital point at 11, he is advantageous because White becomes weaker.]
;W[re]
;B[rd]C[White has to give up the triangled stone if he doesn't want to crawl on the second line.]
;W[qg]
;B[rc]LB[qj:A]C[White needs to play one more move at A. And if he does so, Black will simply walk away in sente.]
))(;B[pc]C[If Black responds to the invasion with this option, White either has the choice to continue or tenuki, as this move doesn't cost anything for White and it creates aji at Black's corner.]
;W[rd]C[Of course, White can still make life...]
;B[qd]
;W[rb]C[In either of the two variations below, White will be able to live although in gote.]
(;B[qb]
;W[rc]
;B[re]
;W[pb]
;B[ob]
;W[qa]
)(;B[re]
;W[pb]
;B[ob]
;W[sc]
;B[pa]
;W[qb]
))(;B[nb]C[Black can also play the second-line hane to attack both White groups.]
(;W[mb]C[If White blocks...]
(;B[pb]C[Black has a few options, one of which is to play the tiger mouth...]
;W[re]
;B[qe]C[The handy bulge at 13 will work well for Black.]
;W[rf]
;B[rd]
;W[qi]C[Black gets sente. There is aji in Black's territory, but White's groups are not particularly thick either.]
)(;B[qd]C[If Black blocks from the other side...]
;W[ob]
;B[pb]LB[na:A]TR[qc]C[Normally White would capture at A and let Black capture the triangled stone, but...]
;W[pc]TR[jc]C[What if White really gets serious here because White has the triangled stone in place?]
;B[oa]
;W[od]
;B[ob]
;W[rc]LB[qb:A]LB[rb:B]C[White can't block at A because Black would pincer at B.]
;B[lb]
;W[lc]
;B[ma]
;W[mc]
;B[rb]C[Depending on the surrounding conditions, this could've got into a huge battle.

-- chat --
trohde: sadly, though, it’s more than I can digest :-! but that has to do with my limited time rather than the review.
trohde: I just LOVE the San-Ren-Sei review.
trohde: Will come back here, though :-)
]
;W[rd]
;B[re]
;W[qe]
;B[pe]
;W[rf]
;B[qf]
;W[se]
;B[rg]
)(;B[ob]C[If Black connects right now, he must be prepared to attack the top White group...]
;W[qe]
;B[pe]
;W[rf]C[Because otherwise White will take a huge corner, and Black will not be happy unless he does some damage on top.]
))(;W[pb]C[In extreme cases, White can solely take the corner.]
;B[ob]
;W[re]C[And of course, this puts the top White group at risk (unless it's very strong.)]
))(;B[pb]C[And, last but not least, Black can choose to focus on the side by playing the second-line kosumi. For White's invasion, he always has a lot of choices.]
;W[qb]
;B[nb]
;W[re]
;B[lc]C[But this will not mean a lot unless Black gains a lot from the attack on top (or in a handicap game.)]
))(;B[kd]C[By the way, if Black aggressively sandwiches White in between by playing the pincer...]
;W[pe]C[White 6 is a good refutation by using Black's weakness in shape.]
;B[qe]
;W[pf]
;B[qf]
;W[qd]
;B[qc]
;W[rd]
;B[rc]
;W[od]
;B[pc]
;W[qg]
;B[re]
;W[rf]
;B[sd]
;W[ph]C[By move 20, White has wrapped Black in the corner and earned a thick potential. The triangled pincer stone is now in danger.]
))(;B[ob]C[[I've seen this a lot. How should White respond?\]
-----------------------------------
White still has a lot of chances, regarding which aspect he is focusing on...]
(;W[nb]C[The most common move for White.]
;B[oc]
(;W[nd]C[[Is this correct, for example?\]
-----------------------------------
Yes! White can alternatively jump out at A.]
(;B[qf]C[[Black should still defend the corner,\]
-----------------------------------
Yes. This is the reasonable move for Black.]
;W[id]C[[and White can extend four spaces and build a big framework.\]
-----------------------------------
Right. This will be an acceptable joseki for both.]
)(;B[ic]C[[How should White proceed in this case?\]
-----------------------------------
Since Black ignores the move at the corner and sandwiches White, White must do something to punish Black in return if Black is not too strong on the right side.]
;W[pe]C[White attaches...]
;B[qe]
;W[pf]
;B[od]
;W[ne]
(;B[oe]
;W[of]
;B[nf]C[Black can venture the push-and-cut if he has influence on both sides...]
;W[qd]
;B[qc]
;W[rd]
;B[re]LB[qb:C]LB[rb:B]LB[rc:A]LB[sc:D]C[White will not be able to crawl at A as Black will play the sequence from B to D.]
;W[rf]
;B[rc]
;W[qf]
;B[sd]
;W[mf]
;B[ng]
;W[oh]C[White is split into two groups. However, he will still be okay if Black doesn't have many of his stones nearby.]
)(;B[qd]C[Otherwise, if Black doesn't cut,]
;W[mg]C[The knight jump by White will fix the weakness with a good shape.]
)))(;W[qf]C[[I've also tried re-approaching\]
-----------------------------------
This move is sometimes useful.]
;B[re]C[[and saw this reaction again.\]
-----------------------------------
Right, this move protects Black's corner maximally and although White gains sente, he doesn't essentially gain much. (The block at A is gote.) Plus, it is difficult for White to connect his two groups together.]
))(;W[pc]C[Personally speaking, this is my favorite move of White making sabaki.]
;B[oc]
;W[od]
(;B[qc]
;W[pe]C[If the ladder is in favor of White, he can make a nice shape out of the exchange.]
;B[pb]
;W[oe]C[Of course, this is somehow of a trick move, so it is still hard to tell which side is more favored.]
)(;B[nd]C[If ladder is not working on White, however...]
;W[oe]
;B[qc]
;W[nb]
;B[pb]C[Black can break White apart, because the triangled stone cannot be captured.]
))(;W[jd]LB[nb:A]C[It is also a good idea for White to quickly spread his stones. If Black continues to crawl on A, White can already tenuki and expand on either side.]
;B[lc]
;W[ld]
;B[md]C[If Black is determined to cause a stir here...]
;W[mc]
;B[nd]
;W[oc]
;B[pc]
;W[lb]
;B[kc]
;W[kd]
;B[kb]
;W[nb]
;B[la]
;W[pb]
;B[qb]
;W[ma]
;B[mb]
;W[od]C[Depending on the number of ko threats Black has, he might alternate his next moves to turn this into a ko battle.]
(;B[oe]
;W[lb]
)(;B[na]
;W[oe]
;B[pa]
;W[me]
))(;W[qf]C[White can also take the sente opportunity to approach the corner from the other side.]
;B[qe]
;W[pf]
;B[oe]LB[ne:A]C[Of course, Black can play the kosumi and split White into two groups. (Another choice would be the knight jump at A.)]
)(;W[re]C[Last but not least, this variant might look a little confusing since the dip at 2-5 is a good move that lies between taking the corner and side.]
;B[qe]
;W[qc]
;B[rf]C[Be prepared, however, that this variation requires a good reading ability to master.]
;W[pc]
;B[oc]
;W[od]
;B[nb]
;W[oe]
;B[mc]
;W[qf]C[The cross cut at 14 is a tesuji for White.]
;B[qg]
;W[pf]
;B[rd]
;W[qd]
;B[se]C[White gains sente, but Black is content with both sides in comfortable shape.]
)))(;B[qd]C[

-- chat --
Ossa13: Thank you!
]
;W[od]
;B[oc]
;W[nc]
;B[pc]
;W[nd]
;B[qg]LB[qf:A]C[[Here the joseki move is at A, but I've seen this move also. I believe this stone can be cut now? If so, how can White take advantage of it?\]
-----------------------------------
Yes, it does leave aji in Black's structure. The best refutation for White, therefore, is to play the regular joseki move and save that aji for later.]
;W[jc]
;B[pp]
;W[qi]
;B[ql]
;W[rf]C[One demonstration of such aji is the peep at 12.]
;B[rg]C[If Black blocks...]
;W[qe]
;B[pe]
;W[pd]C[The cut at 16 can be effectively obnoxious for Black.]
;B[rd]
;W[qc]
;B[qb]
;W[re]
;B[rc]
;W[pf]C[In this variation, for instance, Black either has to give the corner up or suffer a split on the side.
[THE END - Thanks for visiting!\]]
))