Cs> The number of elements in a set. If two sets have the same number of elements (i.e. there is a bijeCtion between them) then they have the same Cardinality. A Cardinality is thus an isomorphism Class in the Category of sets. aleph 0 is defined as the Cardinality of the first infiniteordinal, omega (the number of {natural number}s). (1995-03-29)
