Logic & Fundamentals

Cardinality is a function used to describe the number of elements in a set. We can intuitively describe the cardinality of finite sets. But for infinite sets, the naive concept of "number of elements" becomes vague and unclear. We will now introduce a rigorous way to define cardinality.

We are now able to provide a relatively reasonable definition of cardinality. This article mainly introduces the cardinalities of some common sets and the methods of calculation.