For those of you not reading forums but interested in a positional
judgement after the tower squeeze sacrifice in game 5, an SGF is
attached inline. Conclusion: afterwards White has at least a small lead,
so AlphaGo's strategy was superb.
--
robert jasiek
(;SZ[19]GM[1]CA[UTF-8]FF[4]ST[2]AP[GOWrite:2.3.48]PM[2]RU[Chinese]FG[259:]C[Commentary
by Robert Jasiek
Terms and principles are explained in the book Positional Judgement 1
- Territory.
The file contains markup, same-move variations, same-pass variations,
nodes with SGF diagrams and markup only, variations with SGF diagrams
only. You need a gppd SGF editor to see all diagrams, variations and
markups.]BR[9p]PW[AlphaGo]RO[5]DT[2016-03-15]GN[
]KM[7.50]RE[W+R]PB[Lee Sedol]
;B[qd]
;W[dd]
;B[pq]
;W[dp]
;B[oc]
;W[po]
;B[qo]
;W[qn]
;B[qp]
;W[pm]
;B[nq]
;W[qe]
;B[pe]
;W[qf]
;B[rd]
;W[pf]
;B[ql]
;W[oe]
;B[pl]
;W[ol]
;B[om]
;W[ok]
;B[nm]
;W[qj]
;B[rn]
;W[gq]
;B[cf]
;W[fc]
;B[bd]
;W[ch]
;B[dh]
;W[di]
;B[dg]
;W[cc]
;B[ci]
;W[cj]
;B[bi]
;W[dj]
;B[bh]
;W[ml]
;B[mm]
;W[lm]
;B[nl]
;W[nk]
;B[ln]
;W[ll]
;B[kn]
;W[mn]
;B[mo]
;W[rm]
;B[rl]
;W[ro]
;B[sn]
;W[pn]
;B[oo]
;W[op]
;B[no]
;W[sm]
;B[pp]
;W[nc]
;B[nb]
;W[ob]
;B[pb]
;W[od]
;B[pc]
;W[mb]
;B[oa]
;W[mc]
;PM[2]MN[1]FG[259:]C[Positional judgement of this position. Any
territory uses the concept "current territory".
Preliminary prisoner difference = 1]
;B[tt]C[White can play this forcing sequence with suitable timings.
The positional judgement after the sequence determines the positional
judgement before the sequence.]
;W[rk]
;B[sl]
;W[so]
;B[rn]
;W[pk]
;B[qm]
;W[sn]
;B[on]
;W[qk]C[representative move]
;B[rn]
;L[ec][pe]PM[2]MA[as][bs][cs][cr][dr][ds][er][es][fr][fs][ah][ag][bg][cg][ch][bf][af][ae][ca][da][db][dc][eb][ea][fa][fb][ob][pa][qa][qb][qc][rc][rb][ra][sa][sb][sc][mn][mp][mq][nn][np][nr][ns][op][oq][or][os][pm][pn][po][qn][rm][sm][sn][so][ro][sp][rp][sq][rq][qq][pr][qr][rr][sr][ps][qs][rs][ss][ga][ha][ia][ja][ka][la][nj][nd][ne][nf][ng][of][og][oh][oi][oj][pg][ph][pi][pj][qg][qh][qi][rh][ri][rj][sh][si]C[Follow-up
position after the representative forcing sequence.
Sequence's prisoner difference = 1.
Initial prisoner difference = preliminary prisoner difference +
sequence's prisoner difference = 2.
The intial prisoner difference is used for positional judgement of
this follow-up position.
A ~= -1/2
B = -1
Taking into account the initial prisoner difference 2 and the komi
7.5. According to chapter 4.17, the territory count may approximate
the area count in this game played with area scoring rules.
Territory count = (9 + 11 + 40) - (37,5 + 10) + 2 - 7,5 = 60 - 47,5 +
2 - 7,5 = 7 points in B's favour.]FG[259:]
(
;W[tt]
;B[tt]
;
)
(
;PM[2]C[Start of a reduction sequence determining the territory in the
lower left.]FG[259:]
;W[tt]
;B[cp]
;W[cq]
;B[co]
;W[dq]C[This move is the most peaceful reply when defending the
territory.
Local territory count = -10.
(Negative values favour
White.)]MA[as][bs][cs][cr][dr][ds][er][es][fr][fs]
)
(
;PM[2]FG[259:]
;W[jq]L[lq]C[If we assume this middle game move, then W does not have
any follow-up sente reduction, e.g., A could not be understood as
sente. Therfore it is unhelpful to assume the move as the expected
middle game move for the sake of reducing the lower right territory.]
)
(
;PM[2]C[Determination of the lower right territory.]FG[259:]
;W[iq]C[Some such move can be expected during the middle game if W
plays first on the lower side.]
;B[tt]
(
;W[kq]C[This is the farthest W can extend to reduce in sente. Any
farther extension could not be understood well as a sente.]
(
;PM[2]FG[259:]
;B[lq]
;W[kr]C[The sente move.]
;B[lr]
;W[ls]
;B[ms]
;W[ks]
;B[mr]
;W[kp]
;B[lp]
;W[ko]
;B[lo]
;PM[2]MA[ss][sr][rr][rs][qr][qs][pr][ps][or][os][nr][ns][mq][mp][np][oq][op][qq][rq][rp][sp][sq][so][ro][sn][sm][rm][qn][pm][pn][po][nn][mn]C[Local
territory count = 40.
Note that the earlier prisoners are accounted globally.]FG[259:]
)
(
;B[lr]C[B keeps less.]
)
)
(
;PM[2]FG[259:]
;W[kr]
;B[mr]C[Up to here, it can be called W's sente.]
;W[tt]
;B[kq]C[B has this follow-up forcing sequence.]
;W[jq]
;B[lr]
;W[kp]
;B[lq]
;W[ks]
;B[ls]
;W[jr]L[jp]C[B has less territory than in the standard sente sequence
but the weakness A is a greater disadvantage for W. Therefore, usually
W does not choose the first move of this variation.]
)
)
(
;PM[2]C[Determination of the upper right boundary of the W moyo and
assuming that B cannot threaten to connect to T8 because R9 might be
at T9.]FG[259:]
;W[tt]
(
;B[sf]C[Small monkey. This can be understood as sente.]
;W[sg]
;B[se]
;W[rg]
;B[sk]
;W[sj]
)
(
;PM[2]FG[259:]
;B[sg]C[big monkey]
;W[rg]
;B[se]
;W[sh]
;B[sf]C[Not necessarily sente, especially if R9 is at T9. Therefore,
the big monkey is not chosen for the determination of the upper right
moyo boundary.]
)
)
(
;PM[2]C[Determination of a center boundary of the territory of the W
moyo stretching from the upper to the right side.]FG[259:]
;W[tt]
;B[gd]C[Since peaceful defense is assumed, we can assume a reduction
on the upper side before a reduction of the right center because the
former supports the latter.]
;W[hb]C[This is the most peaceful reply, which does not unnecessarily
help B to better reduce the right center.]
(
;B[lj]C[Reducing the W center is the most valuable action on the
board. Therefore, we may not assume black supporting stones played
before starting the actual reduction of the white moyo for the sake of
positional judgement.
The move is the farthest reduction B can make as sente without being
unreasonable because W would counter-attack any deeper move as an
invasion.]
;W[mj]L[lh][id]C[The most peaceful reply.
Alternative W moves at A or B result in a fight and therefore are not
considered in this sequence of territorial positional judgement.]
;B[lh]
;W[mg]
;B[lg]
;W[mf]
;B[ic]
;W[ib]
;B[jc]
;W[jb]
;B[kc]
;W[kb]
;B[gc]
;W[gb]
;B[fd]
;W[ed]
;B[mi]
;W[ni]
;B[mh]
;W[nh]
;B[lf]
;W[me]
;B[ld]
;W[md]
;B[lc]
;W[lb]C[Note that this sequence only determines W territory\; the B
reduction stones are not meant to build a B moyo because, in a real
game, W would play less passively, prevent a B moyo and nevertheless
protect a similar amount of W territory.]
;L[ec][pe]PM[2]MA[ca][da][db][dc][eb][ea][fa][fb][ga][ha][ia][ja][ka][la][nd][ne][nf][ng][of][og][oh][oi][nj][oj][pj][pi][ph][pg][qg][qh][qi][rh][ri][rj][sh][si]C[A
~= -1/2.
B = -1.
Current territory of the white moyo ~= -37,5.]FG[259:]
)
(
;PM[2]FG[259:]
;B[mh]
;W[kh]C[B must not invade too deeply, or it would not be a peaceful
reduction but a hilarious invasion.]
)
(
;PM[2]FG[259:]
;B[lh]
;W[jh]C[Without first attacking the cutting point, the B reduction
should be attacked from the outside, i.e., is unsuitable as a peaceful
reduction.]
)
(
;PM[2]FG[259:]
;B[id]
;W[je]C[If B reduces from the narrower side, exceptionally W must not
defend passively on the smaller upper side but must defend the widest
open gap of his moyo. Therefore the B move is bad.]
)
(
;PM[2]FG[259:]
;B[je]
;W[kf]
;B[jf]
;W[kg]
;B[kj]
;W[li]
;B[lj]
;W[mj]
;B[ki]
;W[kh]C[B reduces less if he starts reduction from the wrong side.]
)
(
;PM[2]FG[259:]
;B[fj]
;W[hh]
;B[fh]
;W[gf]C[W can sacrifice the marked proto-group to build a greater
center.]MA[di][dj][cj]
)
(
;PM[2]FG[259:]
;B[mj]
;W[lj]
;B[li]
;W[kj]C[This is not a peaceful reduction but a fight. For determining
the current territory, we assume a peaceful reduction so discard a
fight.]
)
)
(
;PM[2]SQ[ni][nh][mk][mj][mi][mh][mg][mf][me][md][gb][gc][hb][hc][ib][ic][jb][jc][kb][kc][lb][lc][gd][hd][id][jd][kd][ld][le][ke][lf][kf][lg][lh][li][lj][lk][km][kl][kk][kj][ki][kh][kg][fd][ed][ee][fe][ge][he][ie][je][ef][ff][gf][hf][if][jf][jg][ig][hg][gg][fg][eg][eh][fh][gh][hh][ih][jh][ji][ii][hi][gi][fi][ei][ej][fj][gj][hj][ij][jj][jk][ik][hk][gk][fk][ek][dk][ck][bk][ak][aj][bj][al][bl][cl][dl][el][fl][gl][hl][il][jl][jm][im][hm][gm][fm][em][dm][cm][bm][am][an][bn][cn][dn][en][fn][gn][hn][in][jn][ao][bo][co][do][eo][fo][go][ho][io][jo][ko][mr][ms][ls][lr][lq][lp][lo][kp][kq][kr][ks][js][jr][jq][jp][ip][iq][ir][is][hs][hr][hq][hp][gp][fp][ep]C[As
we have determined, the territory count is 7 points in B's favour.
Therefore, applying the Excess Principle and the Moyo Principle,
although B has the turn, W must make an excess of more than 7 new
points of territory in the marked valuable region and while settling
the lower left corner. It is reasonable to assume that W succeeds
because his influence dominates the largest, upper part of the
valuable region. His strategy must not be purely, peacefully
territory-defending.
If we think that W's excess will be barely more than 7, he will barely
win the game (my prediction). If we think that he will get a greater
excess, his win will be greater than that of a close game (Kim's
prediction).]FG[259:]
)
)
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