RE: "Semantics" vs. "No Semantics"

> > Formal XQuery semantics are specified using RULES.  
> > Why can't we specify RIF semantics using rules?  
> 
> How would that be different from a proof theory?

It could be a "proof-theoretic semantics" in the style 
of natural deduction. In logic, as you probably know, 
this is considered to be an acceptable alternative 
to Tarski-style model-theoretic semantics.

-Gerd