n. the cardinal number associated with a given class; since two sets are defined to have the same cardinality if their members can be put in one-to-one correspondence, this is an equivalence relation, and the cardinality of any given finite class is taken to be the largest member of the initial sequence of natural numbers (beginning with 1) that so corresponds to it; for example, the cardinality of {knife, fork, spoon}, is
|{knife, fork, spoon}| = |{1, 2, 3}| = 3.
This property may then be used to define arithmetical operations in terms of set operations (see addition). See also aleph.