(;AP[Hexon:0.0]FF[4]GM[11]SZ[11]C[2022/11/11

Black\: Peter
White\: Jack and Dongho

Black wins.

Note\: Jack and Dongho played as a team.
]PL[B]
;B[b4]
;W[swap-pieces]
;B[h4]
;W[e7]
;B[g7]
;W[i9]
;B[f7]
;W[g5]
;B[h5]
;W[h3]
;B[g4]
;W[g3]
;B[i3]
;W[j1]
;B[j3]
;W[k2]
(;B[f4]
 (;W[e3]C[Peter\: This is an obvious losing move, making this variation very short. See the next one, which was also played.]
  ;B[g2]
  ;W[resign])
 (;W[f3]
  ;B[e2]
  ;W[f2]
  ;B[d4]
  (;W[d3]C[Eric\:

The possibility of this move meant this corner was already settled in White's favor.  Playing it now is too soon, since Black can respond with C4.

The variations show how White already had this corner.  (Furthermore, D3 was not just unnecessary\: It should've been harmful, but Black missed the C4 reply.)]
   ;B[e3]
   ;W[e4]
   ;B[d5]
   ;W[e5]
   ;B[c7]
   (;W[d8]C[Peter\: Now Black has an easy win. 

In the next variation, the players switched sides.]
    ;B[b9]
    ;W[b10]
    ;B[c9]
    ;W[c10]
    ;B[d9]
    ;W[d10]
    ;B[f9]
    ;W[resign])
   (;W[e8]C[Peter\: Now I am playing White and Jack and Dongho are playing Black. Can White carve out a win?]
    ;B[d8]
    ;W[c10]
    (;B[b9]C[Peter\: Losing move. Black did have a winning move here, see next variation.]
     ;W[a11]
     ;B[d9]
     ;W[d6]
     ;B[c6]
     ;W[d10]
     ;B[e9]
     ;W[e10]
     ;B[g9]
     ;W[f9]
     ;B[f8]
     ;W[g8]
     ;B[resign])
    (;B[d7]C[Eric\:

Black can also play D7,F9 in the other order.

Peter\: Black can even start with b10.]
     ;W[b10]
     ;B[f9]
     ;W[e9]
     ;B[e6])))
  (;AB[c5][a7][a6]AW[b6]PL[W]
   ;W[b5]C[Eric\:

A height-2 ladder results in White connecting via an extremely short switchback, even without C5.]
   ;B[a5]
   ;W[b3]
   ;B[b4]
   ;W[d3]C[Eric\:

The ladder connects or White wins anyway.])
  (;AB[b6]AW[c5]PL[W]
   ;B[b5]C[Eric\:

If Black yields, then White does the same as before.]
   ;W[c4]C[Eric\:

If Black pushes, then C2 makes a ziggurat.  If Black yields, then White connects with B2 and B4.])))
(;B[i2]C[Eric\:

I in this case, I think Black should push the ladder all the way before jumping, to avoid White getting a forcing move near D2.

I.e., not just F2, see next variation.]
 ;W[i1]
 ;B[h2]
 ;W[h1]
 ;B[g2]
 ;W[g1]
 ;B[e2]
 ;W[f2]
 ;B[e3]
 ;W[f3]
 ;B[e4]
 ;W[f4]C[Peter\: Good point. Now the following might even work.]
 ;B[e5]
 ;W[f5]
 ;B[e6]
 ;W[f6]C[Peter\: Though if White plays e8 instead of f6, it probably does not work this way.]
 ;B[c8]
 ;W[d7]
 ;B[c7]
 ;W[d6]
 ;B[c6]
 ;W[d5]
 ;B[c5]
 ;W[d4]
 ;B[c4]
 ;W[d3]
 ;B[b3])
(;B[f2]C[Eric\:

i.e., not just here,]
 ;W[i2]
 ;B[e4]
 ;W[e3]C[Eric\:

since this would let White get E3.]))
