This follows from the properties of boolean arithmetic, specifically, from the fact that the product ''G''<sub>''ik''</sub>''H''<sub>''kj''</sub> is 1 if and only if both ''G''<sub>''ik''</sub> and ''H''<sub>''kj''</sub> are 1, and from the fact that ∑<sub>''k''</sub>''F''<sub>''k''</sub> is equal to 1 just in case some ''F''<sub>''k''</sub> is 1. | This follows from the properties of boolean arithmetic, specifically, from the fact that the product ''G''<sub>''ik''</sub>''H''<sub>''kj''</sub> is 1 if and only if both ''G''<sub>''ik''</sub> and ''H''<sub>''kj''</sub> are 1, and from the fact that ∑<sub>''k''</sub>''F''<sub>''k''</sub> is equal to 1 just in case some ''F''<sub>''k''</sub> is 1. |