(;AP[HexGui:0.10.GIT]
C[2020/09/18

Black\: Eric
White\: Bian

Handicap\: -1

Black wins.
]
FF[4]GM[11]SZ[11];B[a11];W[d6];W[f6];B[c4];W[d7];B[i6];W[i5];B[g6];W[h4]
;B[g5];W[g4];B[f5];W[f4];B[e5];W[e3];B[b5];W[d4];B[c6];W[b6];B[c5];W[d5]
C[Mohex proves that this position is winning for Black.];B[b8];W[b9];
B[c8];W[c10];B[c9];W[b10];B[d9];W[d10];B[e9]
C[Eric\: I pushed to here because, since I thought connecting through e7 could be pretty useful for me, I did not want We8 to do anything other than block that potential connection.]
;W[e10]
C[The following moves are winning for Black\: 

f9, g9, g8, i8, j7

Everything else in this area is losing.]
(;B[i8]
C[Winning!

See the next variation for a different win that is perhaps easier to analyze.

See also https\://www.hexwiki.net/index.php/Equivalent_patterns#Second_example_game

Eric\: I don't remember if I noticed at this point that e9 was just far-enough along that g7 would connect to it.  

If I did, then that's likely why I played ahead now rather than pushing farther.  Otherwise, this was just me having to judge when I should play ahead.

In either case, my choice of i8 rather than something else was due to i8 being the closer-to-the-corner acute corner move, rather than due to calculation/reading.
h7 would've been farther from more of the empty space and too close to where I was already somewhat-strong (g6+i6).]
;W[f10];B[g9];W[f9];B[g7]
C[This is equivalent to a span, since the empty cell at e6 is effectively equivalent to an empty cell at f6.]
;W[resign])(;B[f9]
C[f9 variation. Note that the empty cell at e6 is equivalent to an empty cell at f6, and therefore g6 forms something equivalent to an interior ziggurat.]
(;W[f10];B[g9];W[g10];B[i9];W[h9];B[j7];W[i8];B[j8];W[i7];B[j6]
C[i6 now acts as the ladder stone for a 3rd row ladder in the opposite direction. By equvialence, f6 can be moved to e6. The resulting interior ziggurat escapes the ladder.]
)(;W[f11]C[If White yields, the situation is not much better.];B[f10];
W[e11];B[h10];W[g10];B[h9];W[g9];B[h7])))
