I've edited something about that into the text. Basically I think it's to do with the symmetry of the words in "one-to-one": it looks like it should go both ways, as "one thing in the domain hits one thing in the range, and vice versa".
by Patrick Stevens Jun 29 2016
I've edited something about that into the text. Basically I think it's to do with the symmetry of the words in "one-to-one": it looks like it should go both ways, as "one thing in the domain hits one thing in the range, and vice versa".