(;CA[ks_c_5601-1987]AB[pp][pn][qq][pj][pd][fc][db]AW[dd][cf][cc][dp][nq][pr][kq]
C[Lecture 1

How to Handle 3-3 Invasion in Sanrensei


Made by lovelove @L19

http\://www.lifein19x19.com/forum/viewtopic.php?f=15&t=7273]
AP[MultiGo:4.4.4]SZ[19]AB[ic]MULTIGOGM[1]
;W[qc]
(;B[pc]C[Black can think of blocking here for the proverb "Block on the wider side".]
;W[qd];B[qe];W[re];B[qf];W[rf];B[qg];W[pb];B[ob];W[qb];B[nc]C[However, now white has good reduction points that can weaken black's influence from the wall.]
(;W[jd])
(;W[je];B[kd];W[hd];B[hc];W[fd]))
(;B[qd]C[This is the correct move.];W[pc];B[oc];W[ob]LB[nc:A][nb:B]C[A is joseki and B is a mistake.]
(;B[nc];W[nb];B[mc];W[rd];B[re];W[rc];B[qf]C[Black stones on the right side are in good positions, working well with black's influence.])
(;B[nb]LB[nc:A][rd:B]C[A is what black wants, white should play B.]
(;W[nc];B[od];W[mb];B[pb];W[na];B[qb];W[kc]C[Black has corner territory with no weak stones.])
(;W[rd];B[re];W[qe]C[Black cannot expect a good result from here.]
(;B[pe];W[rc]LB[qf:A]C[Must play A.]
(;B[qf];W[nc];B[od];W[mb]C[Black's upper side is broken.])
(;B[nd];W[qf];B[rf];W[qg];B[rg];W[qh];B[rh];W[qi];B[ri];W[qj];B[rj];W[qk];B[pb]
C[Black can capture the corner, but this is a disaster.]))
(;B[od];W[rf];B[rc];W[se];B[rb];W[qh]C[Black's sanrensei is broken.])))))