In the description of std::map (https://en.cppreference.com/w/cpp/container/map), it says:
"Everywhere the standard library uses the Compare requirements, uniqueness is determined by using the equivalence relation. In imprecise terms, two objects a and b are considered equivalent (not unique) if neither compares less than the other: !comp(a, b) && !comp(b, a)."
My question is: I think !comp(a, b) && !comp(b, a) is precise here, why the document says it is "imprecise"?