Figure 1.

[figure: ^{\underline{x}^{i}}; x_{i}; ^{\overline{x}^{i}}; x_{i}; ^{˜\underline{x}^{i}}; x_{i} ∩ x̃_{i}; ^{˜\overline{x}^{i}}; w \binom{}{x̃_{i}}= w(x_{i} ∩ x̃_{i})]