> I don't think they're claiming surjectivity here.
What definition of invertible doesn't include surjectivity?
Many? Just add a "by restricting to the image, we may wlog assume surjectivity".
The question is usually more about whether the inverse is also continuous, smooth, easy to compute....etc.
Many? Just add a "by restricting to the image, we may wlog assume surjectivity".
The question is usually more about whether the inverse is also continuous, smooth, easy to compute....etc.