A linear operator \(T\) between two normed spaces \(X\) and \(Y\) is called compact if \(T(B_X)\) is relatively compact in \(Y\), i.e. its closure is compact.
A linear operator \(T\) between two normed spaces \(X\) and \(Y\) is called compact if \(T(B_X)\) is relatively compact in \(Y\), i.e. its closure is compact.