A totally ordered set is said to be well ordered (or have a well-founded
order) iff every nonempty subset
of
has a least element (Ciesielski 1997, p. 38; Moore 1982, p. 2; Rubin 1967,
p. 159; Suppes 1972, p. 75). Every finite totally
ordered set is well ordered. The set of integers , which has no least element, is an example of a set that is
not well ordered.