Two finite sets A and B have the same size, written A~B, iff they have the same number of elements. For a finite set X, show that ~ is an equivalence relation on P(X).
Two finite sets A and B have the same size, written A~B, iff they have the same number of elements. For a finite set X, show that ~ is an equivalence relation on P(X).
Hint: This is the same thing as saying that there exists some bijection $\displaystyle f:A\to B$