Changes

In the universe <math>U = X \times Y</math> the four propositions <math>xy,\ x (\!| y |\!),\ (\!| x |\!) y,\ (\!| x |\!)(\!| y |\!)</math> that indicate the ''cells'', or the smallest regions of the venn diagram, are called ''singular propositions''.  These serve as an alternative notation for naming the points <math>(1, 1),\ (1, 0),\ (0, 1),\ (0, 0),</math> respectively.

In the universe <math>U = X \times Y</math> the four propositions <math>xy,\ x (\!| y |\!),\ (\!| x |\!) y,\ (\!| x |\!)(\!| y |\!)</math> that indicate the ''cells'', or the smallest regions of the venn diagram, are called ''singular propositions''.  These serve as an alternative notation for naming the points <math>(1, 1),\ (1, 0),\ (0, 1),\ (0, 0),</math> respectively.

Thus, we can write ''Df''_''p'' = ''Df''|''p'' = ''Df''|<1, 1> = ''Df''|''xy'', so long as we know the frame of reference in force.

Thus, we can write <math>\operatorname{D}f_p = \operatorname{D}f|_p = \operatorname{D}f|_{(1, 1)} = \operatorname{D}f|_{xy},</math> so long as we know the frame of reference in force.

Sticking with the example ''f''(''x'',&nbsp;''y'') = ''xy'', let us compute the value of the difference proposition ''Df'' at all of the points.

Sticking with the example <math>f(x, y) = xy,\!</math> let us compute the value of the difference proposition <math>\operatorname{D}f</math> at all of the points.

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