(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PW[baduk]PB[movies]AW[pb][oc][pd][of][pf][qf][qh][qi][qj]AB[nb][ob][gc][ic][nc][jd][nd][le][ne]C[Welcome to the first PRO lesson!
Our teacher is Kim Sung-rae, Korean 8dan professional.
For today he prepared a common endgame situation with a surprising twist. 
It shows how seemingly simple endgame can very complicated! Nothing is what it seems. ]
(;B[pa]C[Endgame question: Black plays hane in the corner. How will White answer?  
There are two possible answers: extending and blocking. 

]
(;W[qb]C[Many players play like this. 
Black has aji in the corner, so extending here seems best.

]
;B[qa]
;W[ra]
;B[oa]
;W[rb]C[This is a slightly painful result, black destroys white corner territory in sente.

You might think It is normal, but endgame is not simple like that.


])
(;W[qa]C[The correct move.
Blocking should be your first idea! It's natural.
]
(;B[oa]C[When black simply defends, it is a great result for white.]
;W[qb]C[Black has sente, but white's corner is big.])
(;B[qb]C[Black has a better move.
This cut is very big aji. ]
;W[oa]
;B[qc]C[Sente.]
;W[pc]
;B[ra]
(;W[pa]
;B[sb]C[It seems that white can't play this way. Black makes a living group inside white's corner.]
;W[rc]
;B[rd]
;W[qd]
;B[rb]
;W[re]
;B[sc]C[Black is alive.]
;W[se]
(;B[sd]LB[sa:2][rc:1]C[To understand this situation better, let's count how many points white lost.

Black makes two points of territory and captures one stone. So black gains 3 points.
To know how many points white lost, we have to compare two situations: the one you see now, to when white secures the corner territory. 

(See other variation)



To summarize: black gains 3 points, white loses 9 points. That means that in total, white lost 12 points in the corner.

But here comes the beauty of go:
White has sente and can now destroy blacks territory!]
;W[na]C[This is big.]
;B[lb]
;W[la]
;B[ka]
;W[ma]
;B[kb]
;W[mb]
;B[mc]TR[ka][la][ma][na][kb][lb][mb][mc]C[Black lost 8 points too.
Comparing this to white's 12 point loss, in total white only lost 12-8 = 4 points!

The most important thing is that white still has sente. So white exchanged 4 points of territory for getting sente.
Losing 4 points and sente are exchanged. 

Sente is crucial in endgame. When there is still big endgame to be played, this is good for white!

This is endgame we don't know!]
;AW[cl][cm][cn][fo][dp][fp][eq][dr]AB[gp][hp][ip][jp][lp][fq][nq][er][fr]C[There are situations when you should always block.
Lets have a look at another shape.]
;B[ds]C[In this shape, white should block.]
;W[cs]C[Blocking is the best move here.]
;B[cr]
;W[es]
;B[cq]
;W[dq]
;B[bs]
;W[ds]
;B[ar]
;W[bq]
;B[bp]
;W[cp]
;B[br]
;W[bo]
;B[aq]
;W[ao]
;B[ap]
;W[hr]C[Tesuji.]
;B[ir]
;W[fs]
;B[gq]
;W[is]C[White destroys even more of black's territory and gets sente as well.
 Great for white.
Black's life in the corner was a bad decision.])
(;AE[oa][pa][qa][ra][qb][rb][sb][pc][qc][sc][qd][rd][re][se]C[Let's count the territory when white has the corner.]
;B[pa]
;W[qb]
;B[qa]
;W[ra]
;B[oa]
;W[rb]LB[sa:1][sb:2][qc:5][rc:4][sc:3][qd:6][rd:7][sd:8][qe:9][re:10][se:11][rf:12][sf:13]C[White has 13 points of territory. ]
;AW[oa][pa][qa][pc][qd][re][se]AB[ra][qb][rb][sb][qc][sc][rd][sd]LB[qe:1][rf:2][sf:3]C[When black lives in the corner, white has only 3 of those 13 points left. 
13 -3 = he lost 10 points. But he also captured one black stone. Making his loss 9 points. ]))
(;W[rb]C[White can also play a ko.
But if he doesn't have enough ko threats he will lose many points.]
;B[pa]C[You have to be sure to have enough ko threats, to play this way. Otherwise it will be a disaster.])))
(;AE[pa]AW[rf]SQ[rf]C[When white has a stone on the second line in the vicinity, he should also always block.]
;B[pa]
;W[qa]C[Correct.]
;B[qb]
;W[oa]
;B[qc]
;W[pc]
;B[ra]
;W[pa]
;B[sb]
;W[rc]
;B[rd]
;W[qd]
;B[rb]
;W[sd]C[Tesuji! White can now kill black entirely!]
;B[sc]
;W[se]C[Blacks eye has become false.]))
(;AE[nb][ob][pb][gc][ic][nc][oc][jd][nd][pd][le][ne][of][pf][qf][qh][qi][qj]C[To give you more insight into this endgame, we will show how the position can come into play.]
;B[pd]
;W[nc]
;B[qf]
;W[jd]C[Do you remember this daidaigeima shape from our previous episodes?]
;B[pb]C[When black defends his corner, white has two options. ]
(;W[ne]C[Jumping is a natural move. ]
;B[pj]
;W[ob]C[This kosumi is big. It defends the top territory and also puts pressure on the black corner.]
;B[oc]C[The usual answer.]
;W[nb]C[Black can tenuki or respond locally.]
(;B[qm]C[If black plays tenuki, white has some aji in the corner.]
(;W[qb]C[This clamp is common. ]
(;B[pa]C[Often a dubious answer by black. ]
;W[qc]
;B[pc]
;W[re]
;B[rf]
;W[qe]
;B[pe]
;W[qd]
(;B[sd]LB[pf:A]C[Killing white is not realistic when black still has the weakness at A. ]
;W[se]
;B[qa]
;W[rb]
;B[ra]
;W[sc]
;B[rd]
;W[pf]C[After this cut, black is in trouble. ])
(;B[og]C[Defending is proper.]
;W[sb]C[But white lives. Painful for black. ]))
(;B[qc]C[Instead of trying to kill white, pros often play here instead.
]))
(;W[qc]C[The second way for white to attack the corner.]
;B[pc]
;W[qb]
(;B[pa]C[Reverts to a situation better for white.]
;W[re])
(;B[qd]C[Black can choose to block.]
;W[pa]C[White takes away the corner, but black is solid and has sente.])))
(;B[of]C[A great local move. 
After this, there is no aji in the corner.]
(;W[qb]C[Does not work anymore.]
;B[pa]
;W[qc]
;B[pc]
;W[re]
;B[rf]
;W[qe]
;B[pe]
;W[qd]
;B[sd]
;W[se]
;B[qa]
;W[ra]
;B[rb]
;W[sb]
;B[rc]C[A shortage of liberties for white. White is dead.])
(;W[pa]C[So this is where we come to the endgame play! 
In this position this endgame move is the best white can do.])))
(;W[ob]C[Instead of jumping first, white can also play the kosumi immediately. ]
(;B[oc]LB[pc:A][qc:B]C[Black almost always plays here. 
Black could also play at A or B instead.]
;W[nb]C[After this the corner is still open.]
;B[nd]C[That's why black continues here. 
A standard pattern will follow. ]
;W[md]
;B[me]
;W[qc]
;B[pc]
;W[ne]
;B[od]
;W[ld]
;B[nf]
;W[le]
;B[mf]LB[lb:A]C[Black has bad shape, but his corner is safe. 
Note that A will become the vital point in endgame. ]
;W[pa]C[The endmage move. ]
;B[qa]C[Black should block!]
;W[qb]
;B[oa]
;W[ra]
;B[pa]
;W[sb]
;B[rc]
;W[rd]
;B[qd]
;W[rb]
;B[re]
;W[sc]
;B[se]
;W[sd]C[White can live, but..]
;B[lb]C[Black has a great tesuji.
Black destroys more of white's territory than white destroyed of black's territory. ])
(;B[pc]LB[lc:A]C[This is considered to be a fighting move, it aims at aji around A.]
;W[pa]C[The big drawback is white's endgame sente.]
;B[qa]
;W[oa]
;B[qb])
(;B[qc]C[This move is very secure. But generally it is considered to be too passive.]
;W[pa]C[The good side of it, is that white's hane is not sente anymore.]
;B[qa]
;W[oa]))))
