( ;GM[1]FF[4]CA[UTF-8]AP[Sabaki:0.40.1]KM[6.5]SZ[19]DT[2018-11-24]AB[pd][pp][cq][dq][er][fr]AW[dp][dd][cp][eq][fq][gq]C[In this position, black can tenuki now or push once more at A. If I understand correctly, the issue is that without black A in place, white's descent at A requires a response or else black dies. With A in place, the best white can do by descending is ko for life, but black initiates the ko and the value is large. So, black does not need to respond until white has a sufficiently large ko threat.]LB[gr:A] ( ;B[gr] ( ;W[hq]C[BG: White needs to extend again. Otherwise, black H3, is very good for black.] ;B[cj] ;W[hr] ;B[nq]C[White can now get a ko with A or let black live with B.]LB[bp:B][bq:A] ( ;W[bq] ;B[br] ;W[ar] ;B[bp] ;W[ap] ;B[aq]C[This ko is very big because if black wins, black lives and gets out of the corner. So, white needs a serious ko threat before white can play the ko.] )( ;W[bp]C[This descent is still sente.] ( ;B[bq]C[Black is alive. However, (again, modulo the fact that white's descent this early makes no sense) in this position, black is 10% better off than the same position without the third extension at G2.] )( ;B[cf] ;W[br] ;B[bq] ;W[aq]C[Black is dead.] ) ) )( ;W[cj] ;B[hq] ;W[hp] ;B[ip] ;W[iq] ;B[hr] ;W[ho] ;B[io]C[Very good for black. White's ability to expand their position is being limited. Black is getting some nice influence facing right with a stone at the right 4-4. White is getting some territory, but white can still be reduced.] ) )( ;B[cj] ;W[gr]C[Now, black has to respond or white A kills.]LB[bp:A] ( ;B[bp] ;W[bo] ;B[bq] ;W[cn]C[Black lives, but white also gets a fairly solid position. ] ;B[nq]HO[1]C[While white wouldn't decend so early, this position is directly comparable to the same position after black extends to G2. In this position, Lizzie thinks that the win probability is unchanged from the start of the game.] )( ;B[nq] ;W[bp] ( ;B[bq] ;W[fs] ;B[ds] ;W[bs] )( ;B[br] ;W[ar] ( ;B[bq] ;W[aq] ;B[ds] ;W[fs] )( ;B[aq] ;W[bq] ;B[as] ;W[cr] ;B[dr] ;W[cs] ) ) ) ) )