Changes

The latter proposition may be interpreted as saying "change <math>x\!</math> or change <math>y\!</math> or both".  And this can be recognized as just what you need to do if you happen to find yourself in the center cell and desire a detailed description of ways to depart it.

The latter proposition may be interpreted as saying "change <math>x\!</math> or change <math>y\!</math> or both".  And this can be recognized as just what you need to do if you happen to find yourself in the center cell and desire a detailed description of ways to depart it.

We have just computed what will variously be called the ''difference map'', the ''difference proposition'', or the ''local proposition'' ''Df''_''p'' for the proposition ''f''(''x'',&nbsp;''y'') = ''xy'' at the point ''p'' where ''x'' = 1 and ''y'' = 1.

We have just computed what will variously be called the ''difference map'', the ''difference proposition'', or the ''local proposition'' <math>\operatorname{D}f_p</math> for the proposition <math>f(x, y) = xy\!</math> at the point <math>p\!</math> where <math>x = 1\!</math> and <math>y = 1.\!</math>

In the universe ''U'' = ''X''&nbsp;&times;&nbsp;''Y'', the four propositions ''xy'', ''x''(''y''), (''x'')''y'', (''x'')(''y'') 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 <1,&nbsp;1>, <1,&nbsp;0>, <0,&nbsp;1>, <0,&nbsp;0>, 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 ''Df''_''p'' = ''Df''|''p'' = ''Df''|<1, 1> = ''Df''|''xy'', so long as we know the frame of reference in force.