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C[The Tenuki Strategy
Commentary: Albert Yen 7d
Game Editor: Myron Souris
Published in the March 31, 2020 edition of the American Go E-Journal
In this commentary, Albert describes numerous concrete examples of how stronger players choose where to play in tactical situations. More importantly, these methods are practical for weaker players to use for immediate benefit.
Albert gives this overiew, "I believe that most high dan players don't really think faster than weaker players. Instead, we just have more efficient search algorithms. From personal experience, we only seriously consider 3-5 choices before ultimately deciding where to play, so having a better selection of 3-5 moves is key to improving our play."
Albert goes on to say, "I am sharing a general strategy to find vital points in tsumego and semeai problems. I tried to explain that strategy in my local go club and most people seemed confused, so I am going to flush out the full approach here. I suspect that most strong players already do something similar, but not everyone is aware of it. Obviously, this method doesn't work every time, but is applicable to many situations. If you cannot see the answer to a problem within 10 seconds, I recommend that you try the tenuki strategy to eliminate possibilities, which is what I do personally."
Albert Yen is an 8 dan player from Chicago. He first started playing go at the age of five after watching Hikaru no Go on television, and became 6 dan in Taiwan when he was 7. Albert continued to compete in America after he moved to Chicago in fifth grade and studied under Jiang Mingjiu 7p. To date, he has made several showings in national and international tournaments, including winning representation to the World Youth Goe Championship in 2014, 1st place in the Redmond Cup in 2015, and 4th place at the 2019 World Amateur Go Championship. Albert is currently a second year undergraduate student in UIC's GPPA BA/MD program in Chicago. Outside of go, Albert enjoys running and ping pong.];
C[Follow these steps to "The Tenuki Strategy":
1. Imagine you tenuki and let your opponent play another move locally.
2. See if you can reverse the situation by playing two consecutive moves.
3. If you cannot, then wherever your opponent played is the vital point. Case closed.
4. If only playing at A and B can counter your opponent's move at C, then your only options for your first move are A, B, and C. For this strategy to work effectively, there shouldn't be more than two pairs of A and B that counter your opponent's extra move at C.
5. If many A and B pairs (at least three) can counter your opponent's move at C, then either you haven't found the vital point or this problem shouldn't be solved using this method.
I know this strategy seems very abstract right now, so let's dive into some examples!]
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AW[mm][mn][mo][on][pn][qo][qp][np][nq][nr][rp][rq][or][sr]
AB[no][oo][lp][mp][op][oq][qq][qr][lr][pr][rr]
C[We'll start with a baby example. White to play.
For people, who haven't seen this tesuji, finding the move may be hard. How should White reduce Black's liberties? Obviously White has 4 liberties, but because Black's group is not exactly connected, determining the exact number of Black's liberties is a little tricky.]
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B[pq]
LB[pq:A]
C[Let's assume that Black has a stone at A. Now Black clearly has 6 liberties. White cannot win this semeai, even if White plays 2 moves in a row.
Now you see where I am going, right? Yes, A is the vital point for White too!]
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W[pq]
C[This throw-in is the vital point. This throw-in may not be obvious to some people, but if you see that Black is guaranteed 6 liberties if Black has a stone here, then you would know that White has to play here to win the semeai.];
B[pp]
C[This reduces Black's liberties by 1 in sente. White just needs to reduce liberties as normal to kill Black now.];
W[nn];B[mr];W[po];B[pq];W[rs]
C[Black dies.]
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AW[jf][jg][jh][ih][kh][hi][hj][li][lj][fj][fk][gl][kl][ll][hm][im][jm]
AB[ie][je][ke][if][lf][lg][lh][hg][hh][ii][ji][ki][hk][jk][jl]
C[White to play again. Where's the vital point? Use the same strategy as before.]
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W[jj];B[ij]
LB[kj:A]
C[What now? Don't connect at A too fast!]
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W[ik]
C[Thus this is the move. White wins the liberty race by one.]
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B[il];W[kj];B[ik];W[gk]
LB[il:A]
C[The throw-in forces Black to have an extra stone at A, which reduces Black's liberties by one.]
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B[kj];W[il]
C[White wins the semeai.]
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B[ik]
C[If Black gets this connection Black would get 5 liberties, and White cannot win the semeai even with two consecutive moves.]
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B[jj]
C[If Black connects here everything is over. Thus, White's first move must be here to deny Black 5 liberties.]
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AW[rn][ro][qp][qq][qr][sp][pr]
AB[qm][qn][qo][rm][sm][sn][pp][pq][nq][or]
C[Black to play. This problem is a classic that most people above 1 dan probably know. Here we can also use the vital point principle.]
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W[sr]
LB[rp:A][rq:B][sr:C]
C[If White gets this move, then the only way for Black to play 2 in a row to kill White is if Black gets A and B. Thus, Black's first move must either be at A, B, or C (where White just played).
Sometimes, finding the best move for your opponent is hard, but will improve with practice. Generally, try to look for moves that create distinct eyes, extend liberties through connection, or cut off other groups. Classic proverbs like, "look for 1-2 vital point" or "play in the middle", are also helpful starting points.]
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B[rq]
C[Playing here is silly, which we can quickly eliminate.];
W[rr]
C[White lives.]
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B[sr]
LB[rp:A]
C[Now we're down to either this move or A.];
W[rr]
C[Upon further reading, we can see that White lives with this move.];
B[rp];W[sq];B[so];W[ss]
C[White lives.]
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B[rp]
C[The only possible first move.];
W[rq]
LB[sr:A]
C[Now we can actually use the same principle again. If White gets A, then Black cannot kill White in 2 moves, so A is the vital point.]
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AW[lm][mn][po][pp][oq][qq][qr][lr][mr][nr]
AB[on][pn][qn][qo][qp][np][kq][lq][mq][rq][rr][ir][kr]
LB[op:F][pq:G][pr:C][ls:E][ms:H][os:D][ps:B][qs:A]
C[Bottom right, Black to play. This 4d+ level example is considerably harder, but even more applicable in practice.
The "vital point" is hard to find in this problem. At first glance, A through E all seem possible. Let's break down each one.
If White gets A: Black can play at (C and E) or (E and F) or (C and G)
If White gets B: Black can play at (F and G) or (E and H), *see below
If White gets C: Black can play at (D and F) or (A and D)
If White gets D: Black can play at (A and C) or (C and G) or (E and C)
If White gets E: Black can play at (A and B) or (A and C) or (C and G) or (A and D) or (B and C)
I may have missed some combinations but clear enough is that regardless of where White plays next, Black has multiple pairs of move to kill White. In this scenario, we choose the move with the least number of options for Black, which are B and C, each with two pairs of moves.
If you have done enough problems, though, you'd see that C looks a lot more like a vital point than B. If you cannot see, then you can consider that the pairs of moves following B include E, F, G, and H, while the moves following C are A, D, and F. The moves following C seem simpler, because D repeats twice. From this reasoning, we can also conclude that C is the more likely route to take.
*Technically, A and E is also a possibility to counter White B, but is very hard to see without knowing the answer to the problem, so I purposefully omitted it from the list above.];
LB[op:B][pq:C][ls:D][ms:E][ps:A]
C[Assume A is the vital point of interest. From the list before, we see that Black has to pick a move from A through E.]
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LB[op:B][pq:C][ls:D][ms:E][ps:A]
TR[pr]
C[Again, these are the choices. However, upon further inspection, none of these moves work. White can play at the triangled point to live.
Thus, this branch of the tree is dead, so Black must consider the other option.]
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LB[op:D][pr:A][os:C][qs:B]
C[Now Assume A is the vital point. Then, Black's possibilities are either A, B, C, or D.
D doesn't work. White can simply play at C to live.
I'll show variations for the other three moves.]
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B[pr]
C[Probably most people's first instinct.];
W[ps];B[os];W[qs];B[or];W[ls]
LB[or:B][os:A]
C[However, White lives. Black has no choice but to play A and B. You can actually use "tenuki strategy" to prove that.]
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B[os]
TR[lm][mn]
C[This move seems like a nice tesuji, but doesn't work because of White's marked stones.];
W[ps];B[or]
LB[pr:A]
C[Black cannot play at A, otherwise White just connects and it's the same as Black playing A first (which fails).];
W[ls];B[ns];W[nq];B[rs];W[op]
LB[no:A][pr:B]
C[A and B are miai, so White lives.]
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B[qs]
C[Thus, this hane is the only option left.];
W[ps]
LB[qs:A]
C[This block is the only move for White. I won't explain why, because if you are strong enough to see the hane or patient enough to read through how I got to the hane, you can figure this out yourself.
It seems like we're kind of stuck here. However, the benefit of my strategy is that at some point you'd be 100% sure that you are on the right track, at which point we can just brute force the problem. Again, this tsumego is not easy, so even employing the tenuki strategy still takes a good amount of reading.
This problem took me about 10 minutes, because I was fishing for moves without a systematic approach. Once I switched to the tenuki strategy, I was confident that A is the correct first move, after which I quickly figured out the right follow-up. Knowing the right first move often reduces the number of possibilities by a factor of five to ten, and so using some tricks is very desirable to limit our searches before committing out brains to reading (which is brutal for players of all levels, speaking as an 8 dan player).];
B[ls]
C[After some annoying reading you'll see that this hane is the only move that works. The result is a ko.];
W[op];B[pr];W[rs];B[os];W[or]
C[Ko is the best result for both sides.]
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AW[ra][rb][nb][nc][pc][qc][od]
AB[kb][mb][mc][md][sb][rc][qd][sd][ne][re][of][pf]
C[Extra practice problems. Black plays. Where is the vital point?];
B[ob]
C[The only move.];
W[pa]
C[White's strongest response.];
B[na];W[oa];B[pb];W[qb];B[qa];W[oa];B[pa];W[oc];B[oa];W[ma];B[pa]
C[White dies.]
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AW[gg][hg][ig][jg][kg][ch][dh][eh][fh][bi][bj][bk][ki][cj][ej][jj][jk][lj][ik][hl][hm][hn][ho][cm][cn][fm][fn][eo]
AB[gh][ci][di][ei][fi][ji][dj][dk][hj][hk][ij][ck][ek][fk][gl][gm][dm]
C[This position looks like something that can happen in a game. How should White kill?]
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B[fl]
LB[gi:B][gj:A]
C[If Black gets this move, then White's only choices are A and B. Thus, White's first move is limited to these three options.]
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W[gj]
C[This move appears to work, but...];
B[hh]
C[Black can play here. White has liberty shortage issues.]
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W[ii];B[fj];W[hi];B[gk]
TR[gj]
C[White cannot save the marked stone!]
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W[fj];B[ii]
C[Black lives.]
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W[gi];B[gj]
LB[hh:A][fl:B]
C[A and B are miai.]
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W[fl]
C[Thus, the only move is here. Please confirm that Black is dead.]
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AW[cm][dm][em][cn][fo][go][ho][cp][cq][ip][jp][jq][jr][br][fr]
AB[dn][do][dp][fp][gp][hp][gq][iq][ir][hr]
C[This problem and the next are challenges for your practice. I'll just show the answers.
Black plays. This problem is 5d+ level.];
B[er]
LB[dq:A][dr:B]
C[Only move. If White gets this move, then Black's only choices would be A and B. Seeing that neither A nor B works as Black's first move is easy.
Thinking that B is the vital point is possible as well, but Black has more pairs of moves to choose from.];
W[dr];B[es];W[eq];B[gs];W[fs];B[is]
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AW[dq][eq][fq][iq][ir][cr][dr][gr]
AB[dn][do][dp][gp][hp][ip][jp][bq][br][cq][jq][jr][js]
C[Black to kill.];
B[cs]
LB[er:D][cs:C][fs:A][hs:B]
C[A is an obvious vital point, so Black must choose between A, B, and C. Technically, B and D is also an option, but playing at D is just silly, so we can ignore it. The correct sequence is shown.
All other "vital points" would yield more than one pair of moves for Black to choose from.]
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W[es];B[is];W[hs];B[fr];W[fs];B[hr];W[hq];B[gq]
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W[is];B[fs];W[gs];B[hr]
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