predicate has a particular sort (the single sort in its signature): the
relational extent of the unary predicate is contained in the entity
extent of its sort. However, the free logic construction requires that
we tighten up our axiomatization for models. The logic notion needed
for the free logic construction requires that every sort be the sort of
some unary predicate that is extensionally equivalent to it.<br>
</p>
<h3><a name="Logic"></a>Logic<br>
</h3>
<p>An IFF prologic is an inclusive idea combining 