4.4 Arithmetic expressions
Under "normalization" it uses the undefined term "monomorphic
function".  The term is not defined in Functions and Operators either.
As I recall from abstract algebra, a monomorphism is a one-to-one
homomorphism.  While unary plus and minus are one-to-one,
most of these operators are not.  For example, 1+0 = 0+1, so
addition is many-to-one.
The simplest solution is to drop the use of the term, which adds
nothing to the discussion anyway.  

In prior drafts he term also appears in
4.5.1 "Value comparisons",
Appendix B.2, "Mapping of overloaded internal functions".
I haven't scanned the latest version for all occurrences.