Second, the difference map (or the chordal transformation) D''G'' = ‹D''G''<sub>1</sub>, D''G''<sub>2</sub>› : E''U''<sup> •</sup> → E''X''<sup> •</sup> is defined in component-wise fashion as the boolean sum of the initial proposition ''G''<sub>''i''</sub> and the enlarged proposition E''G''<sub>''i''</sub>, for ''i'' = 1, 2, according to the following set of equations: | Second, the difference map (or the chordal transformation) D''G'' = ‹D''G''<sub>1</sub>, D''G''<sub>2</sub>› : E''U''<sup> •</sup> → E''X''<sup> •</sup> is defined in component-wise fashion as the boolean sum of the initial proposition ''G''<sub>''i''</sub> and the enlarged proposition E''G''<sub>''i''</sub>, for ''i'' = 1, 2, according to the following set of equations: |