ment, PRED holds of those arguments. That is, if the sequences &lt;... ARGN ...&gt; and &lt;... ARGN-PRIME ...&gt; differ at most in their Nth items and both (PRED ... ARGN ...) and (PRED ... ARGN-PRIME ...) hold, then ARGN = ARGN-PRIME (see #$equals). For example, the format of #$biologicalMother's second argument-place is single-entry, since an animal can only have one biological mother. A predicate with a single-entry format argument-place is thus a #$FunctionalPredicate (q.v.) that is functional with re