Please roll this change back. As I explained to Shiro (but accidentally made a private reply), the remark is relevant to the three predicates <, =, > only, and should be placed below the introductory paragraph.
Okay. But it's not going to be clear if we just move it there. We should specify exactly which predicates do not obey the trichotomy law. I assume that you mean mapping=?, mapping<?, and mapping>?, but not mapping<=? and mapping>=?.
How about adding this paragraph below the introductory paragraph?: