For details on quantification, click here . The notation we use is different from that above and depends on whether the relation is a function or a predicate . In both cases, we create a constant to stand for the relation. People will sometimes speak of a slot on a certain constant, or of a constant having slots. A term is basically anything that can be an argument to a predicate or function.
Variables are terms.
Constants , both atomic constants and reified NATs , are terms. Non-reified NATs are terms. Numbers, strings, or even entire formulas can be used as terms. A truth maintenance system is a mechanism whereby a knowledge based system can keep reasonably consistent and truthful as its knowledge changes. TMS relies on the fact that each assertion has its support recorded in the datastructure.