This also means that if we start with a subset \(f\) of \(A \times B\) that satisfies conditions in Equation \ref{6.5.1} and \ref{6.5.2}, then we can consider \(f\) to be a function from \(A\) to \(B\...This also means that if we start with a subset \(f\) of \(A \times B\) that satisfies conditions in Equation \ref{6.5.1} and \ref{6.5.2}, then we can consider \(f\) to be a function from \(A\) to \(B\) by using \(b = f(a)\) whenever \((a, b)\) is in \(f\). In the situation where \(f: A \to B\) is a bijection and \(f^{-1}\) is a function from \(B\) to \(A\), we can write \(f^{-1}: B \to A\).
