(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2] RU[Chinese]SZ[19]KM[0.00] AW[eb][ob][cc][dc][ec][gc][mc][oc][pc][qc][cd][qd][be][ce][qe][re][dm][bn][cn][cp][cq][eq][gq][er]AB[bb][cb][db][pb][qb][rb][bc][rc][bd][rd][sd][bo][bp][bq][cr][dr]C[Fang Tianfeng 8p Life and Death Foundations 3/36 Tianyuanweiqi 围棋死活基础方天丰主讲 天元围棋 29:47 mm:ss Translated by Daniel Hu 6d 20220929 https://www.youtube.com/watch?v=-DSEVPCYvAg&list=PLku534PwIYW0VtXbrS6EcaLAlPaHfjYO5&index=3 Hello to each Go player, welcome to life and death foundations. In the last two episodes, we showed how to attack and defend weiqi's 4 in a row. Today we'll discuss what to do with a bent 4 shape, that is a bent 4 in the corner. Next, we'll look at the board. ... Just remember to live at 1-1. ... 15:22 ] (;B[jj] (;W[] ;B[aa]C[First the upper left is very common in all sorts of teaching books. The very rare move at 1-1, after which it is clear that it is alive.]) (;W[sb]C[If you don't play 1-1 and descend, then W plays here] ;B[pa] ;W[ra]C[This is dead.] ;B[] ;W[oa]C[Later, W plays out the entire rest of the board, filling liberties and fixing ko threats.] ;B[] ;W[se] (;B[] ;W[sa] ;B[] ;W[sc] ;B[qa] ;W[sb] ;B[sa]C[B can only throw in ] ;W[ra]C[Now W takes and as W has fixed all ko threats on the board, B has no ko threats.] ;B[] ;W[sc]C[That is B playing 2 moves elsewhere on the board has no use on the rest of the board. Then W takes with the next move. Just watch out that if there is a seki elsewhere it is troublesome.]) (;AE[db][eb][dc][ec][gc]AW[ba][bb][bc][bd][af][bf]AB[ca][ab][ac][cc][ad][cd][ce][cf][ag][bg][cg]C[If there is a seki and W can't fix the ko threats, then talking continues, that is I'll sacrifice this and the result is decided by play. In a game, one must see the result after the stones are captured. In this situation, W can sacrifice these because B always has the A15 ko threat that W can't remove.]) (;AE[bb][cc][gc]AW[ba][da][ab][db][ad][ed][ae][de][ee]AB[ca][ac][dc][cd][dd]C[This sort of seki where W is lighter, you have to say in the game whether you want it or not, because here B has a ko threat. Whether the ko threat is bigger or not, we don't worry, in the end, you have to say clearly whether you want to live here or there. ] ;B[bb]C[But as for whether this is profitable or not, this isn't a matter for the rules. If this sort of problem arises, then both sides must have to fix all ko threats, and then continue playing. A bent 4 in the corner with a seki on the board isn't dead yet, depending on the surroundings.]))) (;B[jk] (;W[ds]C[How should W kill this? If normal play then ] ;B[ar]C[Hane a bit, tiger a bit, then this will definitely live.]) (;W[ao]C[Hane here ] ;B[bs]C[Tiger also lives.]) (;W[ar]C[This is the vital point, they must play here. ... This sort of shape is always dead, so W must plan for it to progress into this shape.] (;B[br] ;W[ao]C[If connect, then hane] (;B[ds] ;W[bs]C[Descend then hane.] ;B[ap]C[Block, then this is dead, bent 4 in the corner.]) (;B[as] ;W[bs]C[Throw in has no use, you capture.])) (;B[ao] ;W[aq]C[Descend then crawl.] (;B[br] ;W[ds] (;B[cs] ;W[as]C[Connect then hane, block then extend. This is a bent 4 in the corner.]) (;B[as]C[Watch out that throw in has no use.] (;W[bs]C[W mustn't capture] ;B[cs]C[Now, you can't connect, and shorting liberties has no use.] ;W[as] ;B[ap] ;W[ar] ;B[as] ;W[bs] ;B[aq]C[This is already unconditionally alive. W can't connect.]) (;W[cs]C[you must crawl from here so this is dead.]))) (;B[ds] ;W[br]C[Bend doesn't work you have a cut.] ;B[bs] ;W[co]C[Hane then connect. ])))) (;B[jl] ;AE[db][eb][ob][dc][gc][mc][oc][qc][bd][rd][sd][ce]AW[cb][pb][qb][dd][pd][de][af][bf][cf][qf][rf][sf]AB[ba][ra][cd][qd][ae][be][re][se] (;W[kj]C[The point remains how to make a straight 4 and not a bent 4. ] (;B[ce]C[Wherever B plays, B lives. This is the best to live with 5 points. Next we look at how W should kill.]) (;B[] (;W[ce] ;B[bd]C[Atari from outside is B's intention. This is 4 in a row, alive.]) (;W[bd]C[How to break this intention? A reasonable intuition.] (;B[ce] ;W[ad]C[B can't connect,]) (;B[ad]C[ but the order of moves is problematic ] ;W[ce] (;B[bd]C[B can't connect it is 3 in a row.] ;W[ab]) (;B[ab]C[But B can now make it a ko.] ;W[bd]))) (;W[ab]C[W thinks is there a better move. This is a good move. ... Upon the point, B has no way. ... So now it is a dead shape.] (;B[ac] ;W[bd]C[When you atari, now you throw in.] (;B[ce] ;W[ad]C[Can't connect.]) (;B[ad] ;W[ce]C[Can't take.])) (;B[ce] (;W[ac]C[W can crawl or atari. From the point of view of liberties, crawling is better. ... So get into the habit of crawling. This is good habit. Atari is bad habit. Although it is the same in this position, in some situations, only crawl is possible. ] (;B[bd]C[But if you connect, this is gote for B.]) (;B[aa]C[If you atari, then this loses an eyespace, which makes a difference to liberties later.])) (;W[ad] ;B[bd]C[Because W has to take gote here.] ;W[ac]))))) (;W[kk]C[In the upper right, the eyespace is on this side. This shape is the same essentially as the other, the way to kill is basically the same.] ;B[] (;W[sb]C[Also the point, as long as B hasn't yet B hasn't yet connected R17.]) (;W[rd] ;B[sd] ;W[qc] ;B[sb]C[Throw in is still a ko, doesn't work.])) (;W[kl] ;AE[rb][pd][qd][se][sf]AW[pa][qc][qg][rh][qi]AB[sa][qb][rd][rf][rg]C[This can be longer or shorter. Similar shapes.] (;B[] (;W[qa]C[As usual you can't atari.] ;B[rb]C[B just connects.] ;W[sg] ;B[sf]C[This is 4 in a row, alive for sure.]) (;W[sg] ;B[sf] (;W[rb]C[Throw in doesn't work.] ;B[sb] ;W[qa] ;B[sd]C[Making a ko again.]) (;W[sd]C[So first hane then pointing is the standard method.] ;B[sc] ;W[rb]C[This is this shape.]))) (;B[lj] ;AW[oa][ob]AB[pb]C[In this shape, there is no under the stones even if B has another stone because B still can't connect R19.] ;W[sg] ;B[sf] ;W[sd]C[This is also dead.])) (;W[km] ;AE[pb][qb][rc][pd][se]AW[qa][ob][od][qd]AB[qc][rd]C[There is sometimes other shapes where B has more eyespace towards this side. If B finds that they don't have enough eyespace, they need to think of other methods. [DH: basically W has extra power on one boundary chain S16 but the chain is far enough away from cutting point that even capturing boundary stones doesn't secure cut Again the vital points are far enough from each other. This allows life even when too little space.\]] (;B[qb]C[Now connecting, pinching doesn't help on this side.] (;W[sd]C[Because they have a clamp]) (;W[se]C[Turn also works.])) (;B[sc] (;W[se]C[If making shape, W can turn.]) (;W[qb]C[Don't atari] ;B[se]C[This is a ko.])) (;B[se]C[So now B blocks to maximise eyespace.] (;W[qb] ;B[rc]C[If W ataris, B connects, this is 4 in a row, so blocking is very big.]) (;W[sc]C[W still points, B still blocks.] ;B[sb] ;W[rc] ;B[sd] ;W[rc] (;B[sc]C[B can't take.] ;W[qb]) (;B[qb] ;W[sc] ;B[rd]C[Now B takes with an under the stones. When B doesn't have enough eyespace, B must think of ways to make it balloon bigger to have hope.]))) (;B[lj] ;AE[qa][ob]AW[pb]C[This sort of shape is the same.] ;W[] ;B[se]C[Depending on this block to live. It looks like it can't be enough to live, the others can't possibly be enough.] ;W[sc] ;B[sb]C[You block, it is all the same.] ;W[rc] ;B[sd] ;W[rc] ;B[qb]C[This lives.] ;W[sc] ;B[rd]))) (;B[jm] ;AE[rb][qd][sd] (;W[kj]C[When one side can be a capture race, B needs to plan how to live. One side has the other doesn't. How should B live? Now B needs to consider how to make eyes. ... So B must consider tiger mouth. And which tiger mouth. ... This then is the bent 4 in the corner. One is point 2-1, another is to break eyespace from the outside. These are a few common uses in the corner. We have basically finished discussing common life and death in the corner. One is straight four, one is bent four. There are also rarer shapes that we will leave to later. We must be very familiar with the common shapes in a real game.] (;B[rb]C[Connecting dies for sure.] ;W[sd]C[It is W to move.]) (;B[pa]C[Descending doesn't work for sure.] ;W[ra]C[There is a point.] (;B[rb]C[Now if you connect it dies in gote, you can't connect.]) (;B[sd] (;W[rb]C[Descend then either cut or diagonal. Cut is slightly better.] ;B[sb] ;W[se]) (;W[sb]))) (;B[sd] ;W[sb]C[Descend this side then also point.] ;B[rb]C[Connection is death in gote.]) (;B[sb]C[If this side, they have ] ;W[ra]C[a point] ;B[sd] ;W[rb]C[This is a golden chicken standing on one leg, this corner is dead now.]) (;B[ra]C[Hence, B must tiger this side. This is the correct solution. This is alive.] ;W[sb] ;B[pa]C[If W points here, B can bend here.] ;W[rb] ;B[sc]C[Now W can't cut, as B is able to play the liberty.])) (;W[kk] ;AE[ob][pb][mc][oc]AW[nc][qd]C[This shape is very common.] (;B[sb] ;W[ra] ;B[sd]) (;B[pb] ;W[sb]C[Playing other moves will die for sure after the point.] ;AE[sb][pc]AW[nb][oc][oe]AB[ob] ;B[] ;W[sb]C[Sometimes even if it is longer this point also works. This is always going to die.] ;B[rb] ;W[oa]C[All, the eyespace isn't enough.]))) (;B[jn]C[We have so far discussed 4 points. Now we will discuss 6 points.] ;AE[bb][cb][db][eb][qb][rb][bc][cc][dc][ec][gc][mc][bd][cd][sd][be][ce][qe][re][dm][bn][cn][bo][bp][cp][bq][cq][eq][gq][cr][dr][er]AW[oa][od][pd][rd]AB[pa][pc][qc][sc]TB[aa][ba][qa][ra][sa][ab][bb][qb][rb][sb]C[This the basic shape. When it is surrounded, is it alive or dead? There is a theory, a concept in weiqi that surrounding 6 points is alive. Only in very special situations is it dead. It goes without saying that 1 point is dead, 2 is dead. 3 depends on which side plays first. 4 has two types of death (see variations) 5 has two types of death 6 is normally enough to live. There is only one type of death with 6. ... In other words, you just have to remember that if all the liberties are filled, this is dead. If just one liberty is free, it is already a one step ko in the corner's favour. Because you can make a judgement this B group can't possibly be big. If it is not big, there is no chance of all the liberties being filled. Then a liberty free is more likely, and then the one step ko is very small from the point of view of endgame. Because as we have said that for endgame, if B wins the ko, B gets 6 points. For W to win, W needs to atari and then capture and gets 14 points adding 1pt at 1-1 is 15 points. This means this group is 21 points. A normal ko is 2/3 of the value. A one step ko is 1/2, which is 10.5 so the value of one move is very small. About similar size to a hane and connect. (according to Bill Spight, it is 2/5=8.4) So in this situation, W often doesn't defend. It is a one step ko. __ So your intuition should be that 6 in the corner with 2 free liberties is alive. If it only has the corner liberties, then there is a problem. Otherwise on the edge there is no problem. And even less in the centre because centre stones are all connected together. Now you have a concept of the block 6. An important concept in weiqi is that to surround 6 points is to live. This must be memorised. Ok, we'll finish the lecture here. Thanks for watching. ] (;W[kj] ;AB[ca][cb][ac][bc][cc][pq][qq][rq][sq][pr][qr][sr][ps]C[Upper left square 4 Lower right nail 4]) (;W[kk] ;AB[aa][ba][ca][da][db][ac][dc][ad][bd][cd][dd][qo][ro][so][pp][qp][sp][pq][pr][qr][sr][qs][rs][ss]C[Upper left Bulky 5 (knife handle 5) Lower right (Plum blossom 5)]) (;W[kl] ;AB[aa][ba][ca][ab][cb][db][dc][ad][dd][ae][be][ce][de] ;B[] ;AW[da][ea][eb][ec][ed][ee][af][bf][cf][df][ef] (;W[bc]C[This is grape 6.] ;B[] ;W[cc] ;B[] ;W[ac] ;B[] ;W[bd] ;B[] ;W[cd]C[B can't capture because it is bulky five. It is dead shape.]) (;W[]C[However, normally we have stones on the 3rd line, and you can't create grape 6 like that.] ;AW[ha][la][hb][lb][hc][ic][jc][kc][lc]C[We can only make block 6.] ;AE[jc]AW[ka][id][jd][kd]C[Only like this can we create it.])) (;W[km] ;AW[sd]C[When all the liberties are shorted, the situation is different. If were in the centre, then it would still be alive. But in the corner it will die. Even on the side it is alive.] ;B[] ;W[rb]C[Placing here is dead] (;B[ra]C[B's only chance is clamp] ;W[sb]C[W blocks] ;B[qb]C[Now you can't play in here, so this group dies.] ;W[qa]) (;B[sb] ;W[ra]C[This is a bulky five.])) (;W[kn] ;C[If a liberty is free, whichever side it is, you can't point anymore.] ;B[] (;W[rb] ;B[ra] ;W[sb] ;B[qb]C[Because it can atari and live.]) (;AE[pd]AW[sd][pe][qf]C[Of course, whereever the liberty is free, it is the same.] (;W[rb] ;B[ra] ;W[sb] ;B[qb]) (;W[ra]C[W can only point here.] ;B[rb] ;W[qa] ;B[sa] (;W[sb]C[This turns into a ko, it hasn't lived. But this ko is relatively light for B. Because after W wins the ko, W can only connect.] ;B[] (;W[sa] (;B[qb] ;W[ra] ;B[sa]C[This becomes a ko again.]) (;B[]C[B can tenuki.])) (;W[pd]C[Of course atari outside is also the same. And connecting is worse and meaningless because B doesn't have to capture immediately. Upon winning the ko, W can only atari, and then B takes. Equivalently, this is a one step ko, when there is a liberty free.] ;B[] ;W[qb]C[This is 15pts.])) (;W[] ;B[qb]C[B winning ko gets 6 pts])))) (;W[ko] ;AE[pd][qd]AW[sd][pe][qe]C[If two liberties are free, then this is a living group] ;B[] ;W[ra] ;B[rb] ;W[qa] ;B[sa] ;W[sb] ;B[qb]C[B can atari from outside. W can't connect. Then this is alive.]) (;W[kp] ;AB[qh][rh][sh][qi][qj][qk][ql][rl][sl] ;B[]C[On the side even if all outside liberties are filled there is no problem.] (;W[rj] ;B[sj]) (;W[sj] ;B[rj]))))