(;
KM[0.50]
TM[1200]
PW[Yigang Hua]
PB[Yilun Yang]
WR[8p]
BR[7p]
DT[2014-10-26]
PC[IGS-PandaNet]
RE[W+Resign]
C[Cotsen 2014 Demo Game
White:  Yigang Hua 8P
Black:  Yilun Yang 7P
Commentary:  Yilun Yang 7P
Game editor:  Myron Souris
Published in the November 4, 2014 edition of the American Go E-Journal.

In this Cotsen demo game between strong pros, Yilun Yang 7P provides a detailed but clear fuseki analysis that players of all strengths can grasp.  And stronger players will find Yilun Yang's explanation of the middlegame's attack and defense ideas especially insightful.

Yilun Yang 7P is one of the most popular go teachers in the US.  You can reach him at yly_go@yahoo.com.];
B[pd];W[dd];B[pq];W[cp];B[eq];W[qo]
(;
B[pm]
C[The best pincer in this situation.]
(;
W[lp]
C[A way to destroy the lower side.]
(;
B[po]
C[The natural move to punish White's tenuki.]
(;
W[iq]
C[The proper pincer - White has to be defensive on the lower side.]
(;
B[cq]
C[Locally this move is reasonable, but is not proper in this whole board situation in which sente is very important.  See the variation.];
W[bq];B[dp]
(;
W[cr]
C[A strong move!];
B[co];W[dq];B[bp];W[cq];B[eo]
C[This result is a normal joseki, but White ends with sente, which is the key.];
W[qp]
TR[qo]
C[This move helps the weak marked stone.  Black can no longer make an ideal position in this area.];
B[pp]
(;
W[qm]
C[A good forcing move.]
(;
B[qn]
C[A double sente move.];
W[rn];B[pn]
(;
W[ql]
C[A strong move.]
(;
B[rm]
C[The correct direction to cut.]
(;
W[rl]
C[The correct move.];
B[ro];W[sm];B[rp]
C[This result isn't good for Black, because Black cannot easily use the outside thickness when White has a good lower side position.]
(;
W[qh]
C[This move looks slow, but is a good defense, because White needs a base here.
This opening is already not easy for Black, because White has solid positions everywhere and Black cannot easily use all the outside stones.];
B[cf]
C[This move tries to make a position on the left side.];
W[fc]
(;
B[bd];W[nc];B[qf];W[pb];B[qc];W[cc];B[ci]
(;
W[qb]
C[This move is the best way to help the two stones, and put pressure on Black.]
(;
B[nd]
C[A proper way to help Black's weak group.]
(;
W[md]
C[A strong response.]
(;
B[oc]
C[Black must fight here.];
W[ob];B[mc];W[nb];B[lc];W[ld]
TR[md]
C[The best way to help the marked cutting stone.]
(;
B[kc];W[kd];B[ic];W[jd]
(;
B[jc]
(;
W[rd]
C[This move is the best way to live, and puts the most pressure on Black.]
(;
B[ph]
TR[qh]
C[A good forcing move when Black has a weak group, because the marked stone is strong.];
W[qi]
(;
B[gd];W[gc];B[id];W[qd]
(;
B[ne]
C[This move isn't proper, because Black cannot easily attack White's four stones.  See the variation.];
W[lg];B[qg];W[df]
(;
B[cg]
C[The correct response.];
W[nh]
TR[ne]
C[A nice squeeze.  Black's marked stone isn't that useful now.];
B[pi];W[og];B[qj];W[rj];B[pg]
(;
W[if]
C[This nice soft move is the proper way to squeeze when Black's top group has many liberties.]
(;
B[ie]
C[A big mistake.]
(;
W[hf]
C[A strong response.];
B[kf]
C[Black misread here.]
(;
W[me]
C[This move looks ugly, but is good.];
B[je];W[nf]
C[Hurts Black.]
(;
B[kg];W[pe]
C[White makes a big profit here.  Black is behind in territory.];
B[lh];W[mh]
(;
B[lf]
C[Almost a wasted move.  See the variation.];
W[ok];B[ni];W[li];B[mg]
(;
W[mi]
C[A necessary defense.]
(;
B[nj]
C[See the variation.];
W[pj];B[nk];W[oh];B[oi]
C[These exchanges are painful for Black.];
W[qq]
C[Too soon.  Otherwise, White has some forcing moves on the lower side.]
(;
B[qr];W[dn];B[do];W[fp];B[ep];W[er];B[fq];W[gr]
C[A very valuable defensive move.]
(;
B[ki]
C[An important point.  Black must try to develop the open area.];
W[lk];B[kj];W[mk];B[ol];W[jh]
C[Too soon.];
B[ih]
C[The best response.]
(;
W[dj]
C[A nice reduction.]
(;
B[cj];W[dl]
(;
B[hp]
C[Slack.  See the variation.];
W[gl]
C[Now White is comfortable.];
B[ip];W[jq];B[il];W[gq];B[gp];W[fn];B[en];W[em];B[gn];W[eh]
(;
B[ei];W[fi];B[ej];W[fj];B[ek];W[fm];B[fo];W[dh];B[ck];W[gh];B[hj];W[gj]
(;
B[fd];W[ed];B[ff];W[ef];B[fg];W[fh];B[gg];W[ii];B[hg];W[hk];B[ji]
C[Black makes some profit, but not enough.];
W[hh];B[ig];W[nq]
C[So valuable.]
(;
B[nr]
C[An endgame tesuji.]
(;
W[mr]
C[The correct response.];
B[or];W[bc]
C[So valuable.  The game is over.];
B[bn];W[be];B[ce];W[cd];B[bf];W[ad];B[hb];W[gb];B[lo];W[mp];B[ko];W[ij]
C[Black resigns.]
)
    (;
    W[or]
    C[If White splits Black here, ...];
    B[mr];W[oq];B[mq]
    C[... Black has a chance.];
    W[mp];B[np]
    )
)
    (;
    B[bc]
    C[The most valuable move.];
    W[or]
    C[But White has an easy win.]
    )
)
    (;
    B[lr];W[ge]
    )
)
    (;
    B[eg];W[fg];B[ef];W[gh]
    C[White is fine.]
    )
)
    (;
    B[fl]
    C[Black has to squeeze White from here.];
    W[fm];B[em];W[el];B[gm];W[fn];B[en];W[fk];B[gl];W[eh];B[gh]
    C[This result is better for Black than in the game.]
    )
)
    (;
    B[eh]
    C[This move is the way to split White, but capturing White is almost impossible.];
    W[cj];B[bi];W[bn];B[bo];W[dl]
    )
)
    (;
    W[kh];B[ji]
    C[White is heavier.]
    )
)
    (;
    B[dk]
    C[Defends left side territory, but ...];
    W[ji]
    C[... this result isn't good enough for Black.]
    )
)
    (;
    B[rq];W[or]
    )
)
    (;
    B[pj]
    C[Black doesn't have time to connect here.];
    W[nj];B[rk];W[qk];B[ri];W[sk]
    C[Black cannot live inside.]
    )
)
    (;
    W[nj]
    C[If White tries to kill Black here, ...];
    B[mi];W[oi];B[ng];W[mj];B[of]
    C[... this trade isn't good for White.]
    )
)
    (;
    B[li]
    C[Black must extend here instead.]
    )
)
    (;
    B[pe]
    C[If Black saves the weak group here, ...];
    W[kg];B[jg];W[jf];B[ke];W[mf];B[jh];W[ge]
    C[... Black is in trouble.]
    )
)
    (;
    W[lf]
    C[If White connects here, ...];
    B[je];W[nf];B[kg]
    C[... Black splits White's weak groups.];
    W[pe];B[of];W[oe];B[mf]
    )
)
    (;
    W[jf]
    C[If White responds here, ...];
    B[gf]
    C[... Black makes a nice shape.]
    )
)
    (;
    B[gf]
    C[A normal way to get out, but ...];
    W[ie];B[he]
    TR[gf]
    C[... this exchange is so painful for Black - the marked stone becomes a slow move.]
    )
    (;
    B[fd];W[ed];B[ff]
    C[The proper way to get out.]
    )
)
    (;
    W[ie]
    C[Too tight.];
    B[he];W[if];B[gg]
    C[Black makes a nice shape.]
    )
)
    (;
    B[dg];W[ce]
    (;
    B[be];W[cg];B[bf];W[dh];B[eg];W[ch]
    C[This result is really bad for Black.]
    )
        (;
        B[bf]
        C[White gains with this exchange.]
        )
    )
)
    (;
    B[of]
    C[Good for defending.];
    W[lg];B[pi]
    )
)
    (;
    B[ne];W[qd];B[gd]
    )
    (;
    B[of];W[qd]
    )
)
    (;
    B[rc]
    C[Not playable.];
    W[pc];B[qd];W[od];B[ne];W[oe]
    C[Black loses control.]
    )
)
    (;
    W[rc]
    C[A normal way to live, but ...];
    B[rd];W[pc];B[od];W[qd];B[qe];W[of];B[qc];W[rb];B[nf]
    C[... Black isn't that weak.]
    )
)
    (;
    B[hb]
    C[Another way to defend the connection, but ...];
    W[jc];B[jb];W[mb];B[kb];W[gc]
    C[... Black isn't comfortable.]
    )
)
    (;
    B[jc]
    C[Leaves more forcing moves for White.];
    W[kc];B[kb];W[kd];B[lb];W[ib]
    )
)
    (;
    B[ne]
    C[Too slack.];
    W[lc]
    C[This exchange helps White.]
    )
)
    (;
    W[mc];B[ri]
    C[Now this move is possible.]
    (;
    W[qi];B[rh];W[rj];B[qg]
    C[Black settles easily.]
    )
        (;
        W[rh];B[qi];W[ph];B[pi]
        C[Complex.]
        )
    )
)
    (;
    B[ri]
    C[A tesuji, locally.];
    W[rh];B[qi]
    (;
    W[pi];B[ph]
    C[Complex.]
    )
        (;
        W[ph];B[pi];W[oh]
        C[These exchanges hurt Black's top right group.]
        )
    )
)
    (;
    W[ld]
    C[A nice extension, but ...];
    B[jc]
    C[... the top side is too open.];
    W[kc];B[jd]
    )
    (;
    W[kc]
    C[A solid defense, but ...];
    B[jd]
    C[... the top side will be too flat.];
    W[jc];B[hd];W[id];B[ie];W[ic];B[ef]
    )
)
    (;
    B[di]
    C[Good for developing, but not good for making territory.];
    W[dn];B[do];W[dl]
    C[Black cannot easily attack these White stones.]
    )
)
    (;
    W[nc]
    C[A big opening move, but ...];
    B[qj]
    C[... Black severely squeezes White here.]
    )
    (;
    W[qf]
    C[Too far.];
    B[qi]
    C[This move splits White's weak stones.]
    )
)
    (;
    W[ro]
    C[If White defends here, ...];
    B[qk]
    C[... this move is a great tesuji.];
    W[rl];B[pl];W[rk];B[qj]
    C[White is too low.]
    )
)
    (;
    B[ro];W[rp];B[rm];W[so];B[rl];W[qk];B[rk];W[qj];B[rj];W[qi];B[ri];W[qh]
    C[Too bad for Black.]
    )
)
    (;
    W[rl];B[ql];W[rm];B[qk]
    C[White is too low.]
    )
)
    (;
    B[ql]
    C[If Black blocks here, ...];
    W[pn];B[on];W[qn]
    C[... White makes a solid shape, and also leaves cutting points in Black's shape.];
    B[pl];W[qq]
    C[This result is good for White - Black's outside shape isn't good enough.]
    )
)
    (;
    W[qn]
    C[If White extends here, ...];
    B[qm];W[pn];B[on];W[qq];B[rn];W[ro];B[rm];W[pr];B[or];W[qr];B[nq]
    C[... this result is good for Black.]
    )
)
    (;
    W[co]
    C[A normal response, but ...];
    B[cr]
    C[... Black settles easily.];
    W[cl]
    C[White has to make a base here.];
    B[qn]
    C[An easy game for Black.]
    )
)
    (;
    B[en]
    C[Black has to play here, even though this move isn't locally reasonable for defending.];
    W[cm]
    C[Ending with sente is what is important for Black.];
    B[qn]
    TR[qo]
    C[Black can come back here to make an ideal position.  Even though this game is peaceful, Black gains in the lower right, because the marked stone becomes a bad move.]
    )
)
    (;
    W[qp]
    C[Too soon.];
    B[pp];W[qn];B[pn];W[ql];B[jp]
    C[An ideal move.  This result isn't good for White.]
    )
    (;
    W[gq]
    C[Too tight.];
    B[eo];W[dn];B[jq]
    C[This situation isn't easy for White, because Black has more stones on the lower side.]
    )
    (;
    W[hq]
    C[Looks like a nice pincer, but ...];
    B[jq]
    C[... White has a weakness here.]
    )
)
    (;
    B[ip]
    C[If Black extends here, ...];
    W[op];B[oq];W[np];B[rq]
    C[... this result is another game.]
    )
)
    (;
    W[oo];B[np]
    C[Now the lower side is develop-able for Black.]
    )
    (;
    W[on];B[np];W[qq];B[qr];W[pp];B[oq];W[rq];B[jq]
    C[Black makes a nice position on the lower side.]
    )
)
    (;
    B[pl]
    C[If Black chooses a looser pincer here, ...];
    W[no];B[mq]
    C[... Black's lower side is too flat.]
    )
)

