 x Y, the four propositions
xy, x(y), (x)y, (x)(y) that indicate the &quot;cells&quot;,
or the smallest regions of the venn diagram, are
called &quot;singular propositions&quot;.  These serve as
an alternative notation for naming the points
&lt;1, 1&gt;, &lt;1, 0&gt;, &lt;0, 1&gt;, &lt;0, 0&gt;, respectively.

Thus, we can write Df_p = Df|p = Df|&lt;1, 1&gt; = Df|xy,
so long as we know the frame of reference in force.

Sticking with the example f(x, y) = xy, let us compute the
value of the difference propos