This can occur when the range of $\"\"$ is a subset of the domain of $\"\"$ .

For instance, when $\"\"$ and $\"\"$ , the range of $\"\"$ is all real numbers greter than or equal to $\"\"$ .

This range is a subset of the domain of $\"\"$ which is all real numbers greater than or equal to $\"\"$ .

Thus, $\"\"$ exists for all real numbers.