Algebra Know-It-ALL

Part One 169

Question 9-10

What is meant by the cardinality of a set? What is the cardinality of the set N? The set Z? The
setQ? The set R?

Answer 9-10

The cardinality of a set is the number of elements it contains. The sets N, Z, and Q have
cardinality of א 0 (aleph-null). The set R has cardinality larger than א 0.