(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]HA[2]KM[0.00]
PW[Honinbo Shuwa]PB[Hayashi Yubi]WR[7p]BR[6p]DT[1857-11-17]EV[Castle Game, 1857]AB[pd][dp]C[We begin this short episode with a pro-game]RE[B+5.00]
(;W[cd]
;B[qp]
;W[oq]
;B[po]
;W[nc]
;B[np]
;W[mq]
;B[qg]
;W[ed]
;B[cj]
;W[fq]
;B[fp]
;W[gp]
;B[fo]
;W[dq]
;B[cq]
;W[eq]
;B[cp]
;W[jp]
;B[kc]
;W[qc]
;B[pc]
;W[pb]
;B[ob]
;W[qb]
;B[oc]
;W[re]
;B[qe]
;W[qd]
;B[qf]
;W[hc]
;B[pk]
;W[ne]
;B[ke]
;W[nb]
;B[na]
;W[lb]
;B[oe]
;W[nd]
;B[ic]
;W[hd]
;B[nf]
;W[mf]
;B[me]
;W[le]
;B[lf]
;W[md]
;B[mg]
;W[kd]
;B[me]
;W[ld]
;B[ie]
;W[je]
;B[jf]
;W[kf]
;B[kg]
;W[if]
;B[ke]
;W[jd]
;B[ig]
;W[hf]
;B[lo]
;W[hg]
;B[ih]C[Furiously fast fantastic endgame!

This is a position from a Castle game between Hayashi Yubi 6p (playing as black) and Honinbo Shuwa 7p (playing as white) from 1857.

Black is building a big moyo in the centre, and a big territory on the right side. 
White to play. How can white reduce the right side (in sente)?]
(;W[sg]C[Tesuji!]
;B[jo]
;W[io]
;B[kp]
;W[jn]
;B[ko]
;W[in]
;B[jq]
;W[ip]
;B[kr]
;W[ir]
;B[km]
;W[rh]
;B[qi]
;W[ri]
;B[qj]
;W[dk]
;B[dj]
;W[dm]
;B[cn]
;W[cm]
;B[bn]
;W[fk]
;B[jk]
;W[rk]
;B[rj]
;W[sj]
;B[cg]
;W[ql]
;B[pl]
;W[qn]
;B[qq]
;W[cf]
;B[bf]
;W[be]
;B[df]
;W[ce]
;B[bl]
;W[rr]
;B[qr]
;W[pn]
;B[on]
;W[oo]
;B[pm]
;W[qo]
;B[pp]
;W[ro]
;B[rp]
;W[sp]
;B[sq]
;W[so]
;B[rs]
;W[kn]
;B[ln]
;W[lm]
;B[mm]
;W[ij]
;B[ik]
;W[hj]
;B[jj]
;W[kf]
;B[jg]
;W[mf]
;B[ke]
;W[bm]
;B[am]
;W[ch]
;B[bh]
;W[dg]
;B[bg]
;W[dh]
;B[ej]
;W[hk]
;B[ii]
;W[gh]
;B[qk]
;W[rl]
;B[la]
;W[ka]
;B[ma]
;W[pa]
;B[oa]
;W[kb]
;B[dr]
;W[er]
;B[cr]
;W[jr]
;B[kl]
;W[iq]
;B[kq]
;W[of]
;B[ng]
;W[qh]
;B[ph]
;W[ks]
;B[ls]
;W[js]
;B[lr]
;W[go]
;B[fm]
;W[fl]
;B[eh]
;W[eg]
;B[gn]
;W[ei]
;B[fj]
;W[hl]
;B[rf]
;W[sf]
;B[mb]
;W[lc]
;B[ho]
;W[hp]
;B[gr]
;W[gq]
;B[hn]
;W[fi]
;B[af]
;W[bk]
;B[ck]
;W[cl]
;B[al]
;W[bi]
;B[ci]
;W[bj]
;B[ak]
;W[gj]
;B[ai]
;W[ek]
;B[aj]
;W[em]
;B[es]
;W[fs]
;B[ds]
;W[do]
;B[ep]
;W[en]
;B[fn]
;W[co]
;B[bo]
;W[hr]
;B[ae]
;W[ad]
;B[qm]
;W[rm]
;B[gl]
;W[hi]
;B[kf]
;W[me])
(;W[ch]C[When white plays tenuki..]
;B[rf]C[In this case this is not sente for black.]
;W[dj]
(;B[rd]
;W[rc]
;B[se]
;W[pa]C[This move makes miai.]
;B[oa]
;W[ra]C[White is alive.])
(;B[se]C[Black could make a ko, but it is not such a good ko for black]
;W[rd]
;B[rb]
;W[pa]
;B[oa]
;W[ra]
;B[sc]
;W[sd]
;B[sa]
;W[sb]
;B[cc]
;W[dc]
;B[sa]
;W[ck]C[White plays another ko threat.]
;B[qa]C[When black does not respond, white can play another ko threat]
;W[ep]
;B[rc]C[Black can capture, but he had to win the ko twice.])))
(;AE[dp]AB[dd][nd]C[How do we get to the position we just saw?]
;W[cf]C[When white approaches a hoshi, a 4-4 point, the usual response for black is to play the keima.]
(;B[fc]C[The normal move.])
(;B[gc]C[But black can also play the large keima!]
;W[cc]C[Later, or immediately, white can invade the corner. This is the drawback of black's large knight's jump.]
;B[cd]
;W[dc]
;B[ec]
;W[eb]
(;B[fc]
;W[bd]
;B[be]
;W[bc]
;B[ce]C[This is to be expected, a joseki.]
;W[df]
;B[ee]LB[fb:A]C[Here we arrive at an endgame problem. 

First of all, A is sente for black against white's corner. 

If we consider the top side to be black's territory, how can white best reduce it?]
(;W[dp]C[When white plays tenuki, black can play this move in sente..]
;B[fb]C[White has to respond to make his corner alive.]
(;W[db]C[White lives. The famous L+2 group. If you want to know more about this corner group, please watch episode 13.])
(;W[cn]
;B[db]C[If white plays tenuki black can kill the corner.]
;W[cb]
;B[ea]C[White has one eye.]
;W[ab]
;B[ba]
;W[ca]
;B[ad]))
(;W[fb]C[Playing here might seem good, because it is the same point that black would like to occupy. And it seems sente. ]
;B[gb]C[But black can easily bock. There is a better move!]
;W[ga]C[White can not play hane.]
;B[ha]
;W[fa]
;B[db])
(;W[ga]C[The right move to destroy black's top and to keep sente! This is 2 points better in endgame than just extending on the second line.]
;B[ha]
;W[fa]
;B[hb]C[White has sente.])
(;W[ha]C[Just for reference, this is locally an overplay.]
;B[fa]
;W[fb]
;B[gb]
;W[ga]
;B[db]
;W[ea]
;B[da]
;W[fa]
;B[hb]C[White is ruined.]))
(;B[fb]LB[cf:A]C[Because of the stone at A black better not block here. It's dangerous.]
;W[ed]
;B[fc]
(;W[de])
(;W[bd]))
(;AE[cf]LB[cf:A]C[Without a white stone at A, the situation is different.]
;B[fb]C[Black can block here.]
;W[ed]
;B[fc]
;W[bd]
;B[be]
;W[bc]
;B[cf]
;W[db]
;B[ee]C[A classic joseki.]))))