(;CA[utf-8]FF[4]ST[2]RU[Japanese]AB[eo][do][en][em][fl][ci][lo][fp][fq][lq]AW[dn]
[co][go][dp][ip][eq][jq][ck][dl][dm][gm]PL[W]TR[cn][cp]C[As I expect most of you are aware, In the January 10th game Jubango between Lee Sedol and Gu Li kicked off. A game is being played on the last Sunday of each month. This is the first such Jubango between top players in approximately 70 years, and as you'd expect is arousing huge interest. The winner's prize is 900,000 CAD, also the largest winner's prize for a Go tournament to date (other events will have a larger prize pool for the whole field, but this is the largest amount to be awarded to one player).

The first game was won by Lee Sedol, and proved worthy of the hype.  Various public commentaries have been posted\:
   1.  http\://gogameguru.com/go-commentary-lee-sedol-vs-gu-li-jubango-game-1/
   2. Baduk TV transscription of the live commenatary\:
             http\://www.usgo.org/news/2014/01/report-from-korea-jo-hanseung-9p-kuksu-games-available/
   3. KGS plus has the audio commentary available for all (be warned, it is approximately 8 hours)
   4. On badukmovies.com Canada's own Gansheng Shi 1P does a review (subscription required)
   5.  A review aimed at kyu players \: http\://www.bengozen.com/wgw-31-gu-li-vs-lee-sedol-jubango-game-1-amateur-review/

 All of the above are worth a look.  I'm going to take a closer look at this position from early in the game.  How many of you remember the book "Beyond forcing moves"?  It looked at various positions with some aji, and what use could be made of this aji.  Here the aji are the two triangled cutting points.  Usually there was naive sequence, a sequence that gave 80% value, and then something a bit better that was hard to find.  Lee Sedol came up with a sequence here that was definately 100%, and set himself on the path to victory.]
AP[CGoban:3]SZ[19]GM[1]PB[Lee Sedol]PW[Gu Li]KM[7.5]MULTIGOGM[1]
;W[fr]TR[cn][cp]LB[er:B][fr:A]C[White chose this move A to defend the triangled aji.  In hindsight B was probably a better choice, but black's counter was hard to find.  What would you play now?]
;B[hq]TR[gm][go][ip][jq]LB[hp:B][gr:A]C[Even as a "black to play" problem it is hard to come up with this move instead of A.  At this point the triangled stones are becoming weak, so white needs to defend them.  A white exchange of A for the bamboo joint at B will weaken the center even more, so white defends directly in the center.]
;W[im]TR[cn][cp]LB[jm:A]C[In the game Gu Li played this move.  The Go game guru commentary suggested A might have been a bit better(a lighter shape).  Now black has the chance to go back to work on white's weakness again.]
;B[cp]C[Black cut, and the next few moves are forced.];W[cq];B[bp]LB[bo:A][bq:B]
C[Now black  can consider A or B.  To a professional, B will be deemed not acceptable.  Do you know why?  See the variation.]
(;W[bo];B[bq];W[cr];B[br]LB[gr:B][bs:A]C[This is sente.  A  and B can be considered. See the variation for B.]
(;W[bs]C[After look at the variations, you can see why this is correct.  And now it is time for the final tesjui; the one that explains this whole sequence.]
;B[er]LB[gr:A]C[Black cut here!  If Lee blocked with A and white connected all Lee's moves in the corner would do nothing, just waste ko threats.  Blocking with A was always black's privilege.  If you look at earlier variations it should be clear why A can't be played by white now.  ]
;W[es]C[So white takes the stone.];B[gr]LB[dr:B][fs:A]C[Whit can consider A or B.  See the variation for B.]
(;W[fs]TR[kp][lp][mp]LB[ir:B][lr:C][gs:A]C[This is the game sequence.  And the end result is black has gained a sente move at A.  This means B makes an eye in sente.  Each 1/2 eye for a weak group  can be considered worth 5 points, so black has made a 5 point gain.  In the game later white had cut with the triangled stones.  Black was able to play C, and the sente move at A gave black a connection to the group containing A.  This was decisive.])
(;W[dr]LB[kr:C][gs:B][hs:A]C[If white takes here, both A and B will be sente for black, instead of only B being sente(see the continuation to demonstrate why A is sente).  A black stone at A allows black a connection at C.  This is a loss for wihte.]
;B[hs]LB[jr:A]C[If white cuts with A or tenuki's...];B[ep];W[dq];B[cs];W[ds];B[fs]
C[And it is a ko for the corner.]))
(;W[gr]LB[hr:A]C[If black were kind enough to block here white could push and cut, and it would be a great sucess.  But black won't be so friendly..]
;B[hp]LB[ho:B][hr:A]C[Black will play this bamboo joint.  Now white can think about A and B, see the variation for B.]
(;W[hr];B[iq];W[ir];B[jp];W[kp];B[io];W[kq];B[ko]TR[gm][im][go][gp]LB[lp:A]C[Even though white has gained something by creating the cutting point at A and eliminating the adji in the corner, the weakness of the marked stones in the center more than compensates black for this, this variation is unacceptable for white.])
(;W[ho];B[iq];W[jp]C[After these exchanges black can go back and make use of his corner stones.]
;B[ds]LB[er:B][cs:A]C[This is the vital point.  White can consider A and B.  See the variation for A.]
(;W[er];B[ep];W[dq];B[cs]TR[fl][em][en][do][eo][ep][fp][hp][fq][hq][iq]LB[hr:A]
[jr:B]C[After this the black group and the white group in the corner have a capturing race to fight.  White cannot win it cleanly, whatever variation he choses.  And black will get a move around A in, allowing a connnect with B or so later.  This helps the marked black group get stronger.  White cannot chose this.])
(;W[cs];B[er]LB[ep:B][dr:A]C[Just cutting is the correct follow up.  If white A black plays B and white cannot connect.  So..]
;W[bs]LB[ep:B][dq:A]C[This seems to be the way for white  But now black has found the right time for a thow in at A, and then Black can atari at B and white cannot connect.  Again no good for white.]))))
(;W[bq];B[cn];W[bo];B[bn];W[ap];B[bj]TR[ck][dl][dm][dn]SQ[bn][cn]C[Here, this black move will be sente, threating to cut off the triangled stones.  The difference in endgame where this is sente for black versus white have a 50% chance of getting it is too large.  If white ignores this how should black connect his marked stones?]
(;B[am]C[Normally black plays here. But..];W[bl];B[al];W[an]LB[bm:A]C[Black cannot connect at A.  So this variation is only a ko to connect.])
(;B[bl]C[This is the correct answer.  But you need to be careful..];W[bk];B[ak]
;W[bm]C[How do you handle this move?]
(;B[cm];W[an];B[am];W[cl]C[Oops!  White has gotten a ko.])
(;B[an]C[This is the answer.  White can do nothing.]))))