  The Q in question is defined by the requirement:
&quot;Having at least 2 of the 3 features in the set {u, v, w}&quot;.

Taking the symbols u = &quot;round&quot;, v = &quot;doubly outlined&quot;, w = &quot;centrally dark&quot;,
and using the corresponding capitals to label the circles of a venn diagram,
we get a picture of the target set Q as the shaded region in Figure 1.  Using
these symbols as &quot;sentence letters&quot; in a truth table, let the truth function q
mean the very same thing as the express