(;AP[HexGui:0.10.GIT]
C[2021/02/12

Black\: Peter
White\: Bian

White wins.
]FF[4]GM[11]PL[B]
SZ[11];B[a7];W[swap-pieces];B[i3];W[g6];B[h7];W[i5];B[f6];W[h2];B[g2];
W[g3];B[g4];W[j1](;B[j5]
C[Eric\: I would have played j3, see next variation.];W[j4]
C[Eric\:

This creates a height-3 cavern (under H7) into which White has all ladders, so J5 is completely useless
and White has the entire K11 side of the K edge.]
(;B[e4];W[e3];B[f3];W[h1];B[f2];W[f1];B[e2];W[e1];B[c2];W[d2];B[c3];
W[d6];B[c7];W[d7];B[f5];W[d8];B[c8];W[c9];B[c6];W[f7];B[a10];W[c4];B[b6]
;W[a5];B[d3];W[d5];B[resign])(;B[c4]
C[Eric\:


maybe this instead?

(It may be easier to think of {G1,G2,H1} as being empty, since both with its pieces and with no pieces, whoever plays there wins that whole region.)]
))(;B[j3]
C[Eric\:

This means Black might eventually get a useful forcing move at J6.]
;W[k1];B[j6]
C[Eric\:

White would ignore this if Black tried it now, but this could become a forcing move if play goes around the F6 piece and towards the K11 corner.]
;W[k4]))
