Description:Alasdair Ian Fenton Urquhart. M.A., University of Edinburgh, 1967. M.A. , University .. A formula A is true in Q if o ķ A, r-valid if true in all r-models. 2. 3 Axiomatization of 8 -. F is axiomatized by the . With these facts in mind, we define an r "T-model to be a triple Q = (S, 5, F) where. (i