# Cardinality

##### Updated: October 21, 2020

## Equality in Cardinality #

Two sets \(X\) and \(Y\) are equal *iff* there exists a bijection \(f : X \longrightarrow Y\) from \(X\) to \(Y\).

Two sets \(X\) and \(Y\) are equal *iff* there exists a bijection \(f : X \longrightarrow Y\) from \(X\) to \(Y\).