I agree that FP isn't more mathematical than other forms of programming. the operational semantics of functional languages are much more well-defined. No

I agree that FP isn't more mathematical than other forms of programming. the operational semantics of functional languages are much more well-defined. No. The operational semantics of any language that has a compiler or interpreter is as well-defined as possible. What you may mean is that the meta-theory of (pure) FP is better understood than the meta-theory of other paradigms, typically because FP has simpler meta-theoretic properties. Logic programming is itself firmly based in axiomatic semantics This is a non-standard use of the term "axiomatic semantics" which is usually referring to Hoare-logic with pre- and post-conditions. Prolog has (simplifying a bit) a proof-theoretic / proof-search / resolution-unification-based semantics. [Hoare-logics for imperative languages] is comparatively understudied, though. That used to be the case, but the last decade has seen extreme progress in this matter, and Hoare logics for imperative languages are routinely used these days.