In this common corner formation, w has a move that will ruin b's day.
(;AP[goproblems]AB[ba]AB[bb]AB[cc]AB[cd]AB[be]AB[bf]AB[af]AW[ca]AW[cb]AW[db]AW[dc]AW[dd]AW[ce]AW[cf]AW[cg]AW[bg]AW[ag]C[White's move, you need to kill the group in the corner](;W[bc];B[bd];W[ac]C[RIGHT])(;W[bd];B[bc](;W[ae]C[RIGHT])(;W[ad]C[RIGHT]))(;W[ab];B[bc](;W[ad];B[ac])(;W[ac];B[ad])(;W[bd];B[ad])(;W[ae];B[ad]))(;W[ac];B[bc](;W[ad];B[ab])(;W[ab];B[ad])(;W[bd];B[ad])(;W[ae];B[ad]))(;W[ad];B[bd](;W[ab];B[ac])(;W[ac];B[ab])(;W[bc];B[ac])(;W[ae];B[ac]))(;W[ae];B[ad]))