Controlling Production Firing: The FCL Language

While implementing a d iagnost ic expert system, FAITH, we have developed a new language, FCL, for c o n t r o l l i n g the f i r i n g of product ions. FCL grea t ly s i m p l i f i e s the task of the user to d i r ec t t h i s f i r i n g in a coherent and purposeful way without s a c r i f i c i n g some of the main advantages enjoyed by product ion systems. One of the i n t e r e s t i n g features of the language is the use of dec la ra t i ve forms to d i r ec t the f i r i n g of proper product ion sequences in a d iagnost ic expert system. Declarat ive forms which represent c i r c u i t diagrams and problem fam i l i es con t ro l goa l -d i rec ted processes l i k e t r ac ing through c i r c u i t s and searching f o r symptoms to conf irm or deny c lose ly re la ted problems. Because we have the FCL f a c i l i t y at our d i sposa l , we have been able to incorporate a la rger than usual number of d iagnost ic s t ra teg ies in FAITH, w i t h the assurance that they w i l l be employed under the r i g h t circumstances.