The Interaction with Incomplete Knowledge Bases: A Formal Treatment

Some formal representa t ion Issues under ly ing the I n t e r a c t i o n between an expert system and I t s knowledge base are d iscussed. I t Is argued tha t a language that can re fe r both to the a p p l i c a t i o n domain and to the s ta te of the knowledge base Is requ i red to spec i fy and to quest ion an incomplete knowledge base. A formal l o g i c a l language w i t h t h i s a b i l i t y is presented and i t s semantics and proof theory are de f i ned . I t is then shown how t h i s language must be used to i n t e r a c t w i t h the knowledge base.