(;AB[pd]AB[dp]AB[sq]AB[rr]AB[rp]AB[qp]AB[qo]AB[qr]AB[pr]AB[pq]AW[pp]AW[po]AW[pn]AW[pm]AW[qn]AW[ro]AW[oq]AW[np]AW[cc]AB[on]LB[gq:a]LB[qg:b]C[Which is the better play for black, a or b?FORCE]AP[goproblems] (;B[qg]C[FORCE];W[fq]LB[dn:X]C[Play at XFORCE];B[dn]C[FORCE];W[ip]LB[nr:a]TR[pr]C[That's right. White's territory at the bottom is not very secure. White's formation is susoaki, 'open at the bottom'. Black can later extend to 'a' from the marked stone and considerably reduce it.RIGHT]) (;B[gq]C[FORCE];W[qf]LB[nd:X]C[Play at XFORCE];B[nd]C[FORCE];W[of]TR[pm]TR[qn]TR[ro]TR[of]TR[qf]C[White's stones are working together to effectively enclose the whole right side. This was a really big play for white.]))