ed expression built from that function or predicate (i.e. a closed expression that has the constant that denotes that function or predicate in its initial or 0th argument-place). An evaluation of this sort is carried out, for example, when the system is queried using an #$evaluate (q.v.) sentence. As one might expect, most evaluatable relations are mathematical or syntactic in nature; for numbers, sets, lists, and strings are the sorts of things that are related in various ways that can be calculated algori